Adding upstream version 126.0.upstream/126.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

308 files changed, 4601 insertions, 4890 deletions

diff --git a/layout/base/AccessibleCaretManager.cpp b/layout/base/AccessibleCaretManager.cpp
index 17597d287d..99155133cd 100644
--- a/layout/base/AccessibleCaretManager.cpp
+++ b/layout/base/AccessibleCaretManager.cpp
@@ -222,27 +222,17 @@ bool AccessibleCaretManager::IsCaretDisplayableInCursorMode(
   if (!caret || !caret->IsVisible()) {
     return false;
   }
-
-  int32_t offset = 0;
-  nsIFrame* frame =
-      nsCaret::GetFrameAndOffset(GetSelection(), nullptr, 0, &offset);
-
-  if (!frame) {
-    return false;
-  }
-
-  if (!GetEditingHostForFrame(frame)) {
+  auto frameData =
+      nsCaret::GetFrameAndOffset(nsCaret::CaretPositionFor(GetSelection()));
+  if (!GetEditingHostForFrame(frameData.mFrame)) {
     return false;
   }
-
   if (aOutFrame) {
-    *aOutFrame = frame;
+    *aOutFrame = frameData.mFrame;
   }
-
   if (aOutOffset) {
-    *aOutOffset = offset;
+    *aOutOffset = frameData.mOffsetInFrameContent;
   }
-
   return true;
 }
 
@@ -1333,10 +1323,9 @@ nsPoint AccessibleCaretManager::AdjustDragBoundary(
     const nsPoint& aPoint) const {
   nsPoint adjustedPoint = aPoint;
 
-  int32_t focusOffset = 0;
-  nsIFrame* focusFrame =
-      nsCaret::GetFrameAndOffset(GetSelection(), nullptr, 0, &focusOffset);
-  Element* editingHost = GetEditingHostForFrame(focusFrame);
+  auto frameData =
+      nsCaret::GetFrameAndOffset(nsCaret::CaretPositionFor(GetSelection()));
+  Element* editingHost = GetEditingHostForFrame(frameData.mFrame);
 
   if (editingHost) {
     nsIFrame* editingHostFrame = editingHost->GetPrimaryFrame();
@@ -1471,8 +1460,7 @@ void AccessibleCaretManager::DispatchCaretStateChangedEvent(
 
   // Send isEditable info w/ event detail. This info can help determine
   // whether to show cut command on selection dialog or not.
-  init.mSelectionEditable =
-      commonAncestorFrame && GetEditingHostForFrame(commonAncestorFrame);
+  init.mSelectionEditable = GetEditingHostForFrame(commonAncestorFrame);
 
   init.mBoundingClientRect = domRect;
   init.mReason = aReason;
diff --git a/layout/base/MotionPathUtils.cpp b/layout/base/MotionPathUtils.cpp
index 4045f2304a..d620064b73 100644
--- a/layout/base/MotionPathUtils.cpp
+++ b/layout/base/MotionPathUtils.cpp
@@ -434,7 +434,7 @@ Maybe<ResolvedMotionPathData> MotionPathUtils::ResolveMotionPath(
 
 static inline bool IsClosedLoop(const StyleSVGPathData& aPathData) {
   return !aPathData._0.AsSpan().empty() &&
-         aPathData._0.AsSpan().rbegin()->IsClosePath();
+         aPathData._0.AsSpan().rbegin()->IsClose();
 }
 
 // Create a path for "inset(0 round X)", where X is the value of border-radius
@@ -466,8 +466,8 @@ static already_AddRefed<gfx::Path> BuildDefaultPathForURL(
     return nullptr;
   }
 
-  Array<const StylePathCommand, 1> array(StylePathCommand::MoveTo(
-      StyleCoordPair(gfx::Point{0.0, 0.0}), StyleIsAbsolute::No));
+  Array<const StylePathCommand, 1> array(StylePathCommand::Move(
+      StyleByTo::By, StyleCoordinatePair<StyleCSSFloat>{0.0, 0.0}));
   return SVGPathData::BuildPath(array, aBuilder, StyleStrokeLinecap::Butt, 0.0);
 }
 
@@ -695,6 +695,21 @@ already_AddRefed<gfx::Path> MotionPathUtils::BuildSVGPath(
                                 0.0);
 }
 
+static already_AddRefed<gfx::Path> BuildShape(
+    const Span<const StyleShapeCommand>& aShape, gfx::PathBuilder* aPathBuilder,
+    const nsRect& aCoordBox) {
+  if (!aPathBuilder) {
+    return nullptr;
+  }
+
+  // For motion path, we always use CSSPixel unit to compute the offset
+  // transform (i.e. motion path transform).
+  const auto rect = CSSRect::FromAppUnits(aCoordBox);
+  return SVGPathData::BuildPath(aShape, aPathBuilder, StyleStrokeLinecap::Butt,
+                                0.0, rect.Size(),
+                                rect.TopLeft().ToUnknownPoint());
+}
+
 /* static */
 already_AddRefed<gfx::Path> MotionPathUtils::BuildPath(
     const StyleBasicShape& aBasicShape,
@@ -725,12 +740,22 @@ already_AddRefed<gfx::Path> MotionPathUtils::BuildPath(
     case StyleBasicShape::Tag::Polygon:
       return ShapeUtils::BuildPolygonPath(aBasicShape, aCoordBox,
                                           AppUnitsPerCSSPixel(), aPathBuilder);
-    case StyleBasicShape::Tag::Path:
+    case StyleBasicShape::Tag::PathOrShape: {
       // FIXME: Bug 1836847. Once we support "at <position>" for path(), we have
       // to also check its containing block as well. For now, we are still
       // building its gfx::Path directly by its SVGPathData without other
       // reference. https://github.com/w3c/fxtf-drafts/issues/504
-      return BuildSVGPath(aBasicShape.AsPath().path, aPathBuilder);
+      const auto& pathOrShape = aBasicShape.AsPathOrShape();
+      if (pathOrShape.IsPath()) {
+        return BuildSVGPath(pathOrShape.AsPath().path, aPathBuilder);
+      }
+
+      // Note that shape() always defines the initial position, i.e. "from x y",
+      // by its first move command, so |aOffsetPosition|, i.e. offset-position
+      // property, is ignored.
+      return BuildShape(pathOrShape.AsShape().commands.AsSpan(), aPathBuilder,
+                        aCoordBox);
+    }
   }
 
   return nullptr;
diff --git a/layout/base/PresShell.cpp b/layout/base/PresShell.cpp
index 31c21c3377..7674abb3d0 100644
--- a/layout/base/PresShell.cpp
+++ b/layout/base/PresShell.cpp
@@ -14,6 +14,7 @@
 #include "mozilla/dom/AncestorIterator.h"
 #include "mozilla/dom/FontFaceSet.h"
 #include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/FragmentDirective.h"
 #include "mozilla/dom/LargestContentfulPaint.h"
 #include "mozilla/dom/MouseEventBinding.h"
 #include "mozilla/dom/PerformanceMainThread.h"
@@ -1281,10 +1282,13 @@ void PresShell::Destroy() {
 
   ClearApproximatelyVisibleFramesList(Some(OnNonvisible::DiscardImages));
 
-  if (mCaret) {
+  if (mOriginalCaret) {
+    mOriginalCaret->Terminate();
+  }
+  if (mCaret && mCaret != mOriginalCaret) {
     mCaret->Terminate();
-    mCaret = nullptr;
   }
+  mCaret = mOriginalCaret = nullptr;
 
   mFocusedFrameSelection = nullptr;
 
@@ -2238,9 +2242,20 @@ PresShell::GetAccessibleCaretEventHub() const {
   return eventHub.forget();
 }
 
-void PresShell::SetCaret(nsCaret* aNewCaret) { mCaret = aNewCaret; }
+void PresShell::SetCaret(nsCaret* aNewCaret) {
+  if (mCaret == aNewCaret) {
+    return;
+  }
+  if (mCaret) {
+    mCaret->SchedulePaint();
+  }
+  mCaret = aNewCaret;
+  if (aNewCaret) {
+    aNewCaret->SchedulePaint();
+  }
+}
 
-void PresShell::RestoreCaret() { mCaret = mOriginalCaret; }
+void PresShell::RestoreCaret() { SetCaret(mOriginalCaret); }
 
 NS_IMETHODIMP PresShell::SetCaretEnabled(bool aInEnable) {
   bool oldEnabled = mCaretEnabled;
@@ -3277,6 +3292,46 @@ nsresult PresShell::ScrollToAnchor() {
       ScrollAxis(), ScrollFlags::AnchorScrollFlags);
 }
 
+bool PresShell::HighlightAndGoToTextFragment(bool aScrollToTextFragment) {
+  MOZ_ASSERT(mDocument);
+  if (!StaticPrefs::dom_text_fragments_enabled()) {
+    return false;
+  }
+  const RefPtr<FragmentDirective> fragmentDirective =
+      mDocument->FragmentDirective();
+
+  nsTArray<RefPtr<nsRange>> textDirectiveRanges =
+      fragmentDirective->FindTextFragmentsInDocument();
+  if (textDirectiveRanges.IsEmpty()) {
+    return false;
+  }
+
+  const RefPtr<Selection> targetTextSelection =
+      GetCurrentSelection(SelectionType::eTargetText);
+  if (!targetTextSelection) {
+    return false;
+  }
+  for (RefPtr<nsRange> range : textDirectiveRanges) {
+    targetTextSelection->AddRangeAndSelectFramesAndNotifyListeners(
+        *range, IgnoreErrors());
+  }
+  if (!aScrollToTextFragment) {
+    return false;
+  }
+
+  // Scroll the last text directive into view.
+  nsRange* lastRange = textDirectiveRanges.LastElement();
+  MOZ_ASSERT(lastRange);
+  if (RefPtr<nsIContent> lastRangeStartContent =
+          nsIContent::FromNode(lastRange->GetStartContainer())) {
+    return ScrollContentIntoView(
+               lastRangeStartContent,
+               ScrollAxis(WhereToScroll::Center, WhenToScroll::Always),
+               ScrollAxis(), ScrollFlags::AnchorScrollFlags) == NS_OK;
+  }
+  return false;
+}
+
 /*
  * Helper (per-continuation) for ScrollContentIntoView.
  *
@@ -4473,6 +4528,26 @@ MOZ_CAN_RUN_SCRIPT_BOUNDARY void PresShell::ElementStateChanged(
   }
 }
 
+MOZ_CAN_RUN_SCRIPT_BOUNDARY void PresShell::CustomStatesWillChange(
+    Element& aElement) {
+  if (MOZ_UNLIKELY(!mDidInitialize)) {
+    return;
+  }
+
+  mPresContext->RestyleManager()->CustomStatesWillChange(aElement);
+}
+
+MOZ_CAN_RUN_SCRIPT_BOUNDARY void PresShell::CustomStateChanged(
+    Element& aElement, nsAtom* aState) {
+  MOZ_ASSERT(!mIsDocumentGone, "Unexpected CustomStateChanged");
+  MOZ_ASSERT(aState, "Unexpected empty state");
+
+  if (mDidInitialize) {
+    nsAutoCauseReflowNotifier crNotifier(this);
+    mPresContext->RestyleManager()->CustomStateChanged(aElement, aState);
+  }
+}
+
 void PresShell::DocumentStatesChanged(DocumentState aStateMask) {
   MOZ_ASSERT(!mIsDocumentGone, "Unexpected DocumentStatesChanged");
   MOZ_ASSERT(mDocument);
@@ -5582,7 +5657,7 @@ nsresult PresShell::SetResolutionAndScaleTo(float aResolution,
 
   // GetResolution handles mResolution being nothing by returning 1 so this
   // is checking that the resolution is actually changing.
-  bool resolutionUpdated = (aResolution != GetResolution());
+  bool resolutionUpdated = aResolution != GetResolution();
 
   mLastResolutionChangeOrigin = aOrigin;
 
@@ -5647,7 +5722,9 @@ void PresShell::SetRenderingState(const RenderingState& aState) {
 }
 
 void PresShell::SynthesizeMouseMove(bool aFromScroll) {
-  if (!StaticPrefs::layout_reflow_synthMouseMove()) return;
+  if (!StaticPrefs::layout_reflow_synthMouseMove()) {
+    return;
+  }
 
   if (mPaintingSuppressed || !mIsActive || !mPresContext) {
     return;
@@ -5660,8 +5737,9 @@ void PresShell::SynthesizeMouseMove(bool aFromScroll) {
     return;
   }
 
-  if (mMouseLocation == nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE))
+  if (mMouseLocation == nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE)) {
     return;
+  }
 
   if (!mSynthMouseMoveEvent.IsPending()) {
     RefPtr<nsSynthMouseMoveEvent> ev =
@@ -11220,8 +11298,7 @@ Maybe<MobileViewportManager::ManagerType> UseMobileViewportManager(
   if (nsLayoutUtils::ShouldHandleMetaViewport(aDocument)) {
     return Some(MobileViewportManager::ManagerType::VisualAndMetaViewport);
   }
-  if (StaticPrefs::apz_mvm_force_enabled() ||
-      nsLayoutUtils::AllowZoomingForDocument(aDocument)) {
+  if (nsLayoutUtils::AllowZoomingForDocument(aDocument)) {
     return Some(MobileViewportManager::ManagerType::VisualViewportOnly);
   }
   return Nothing();
@@ -11244,6 +11321,11 @@ void PresShell::MaybeRecreateMobileViewportManager(bool aAfterInitialization) {
     return;
   }
 
+  if (!mPresContext->IsRootContentDocumentCrossProcess()) {
+    MOZ_ASSERT(!mMobileViewportManager, "We never create MVMs for subframes");
+    return;
+  }
+
   if (mMobileViewportManager) {
     // We have one, but we need to either destroy it completely to replace it
     // with another one of the correct type. So either way, let's destroy the
@@ -11253,16 +11335,6 @@ void PresShell::MaybeRecreateMobileViewportManager(bool aAfterInitialization) {
     mMVMContext = nullptr;
 
     ResetVisualViewportSize();
-
-    // After we clear out the MVM and the MVMContext, also reset the
-    // resolution to its pre-MVM value.
-    SetResolutionAndScaleTo(mDocument->GetSavedResolutionBeforeMVM(),
-                            ResolutionChangeOrigin::MainThreadRestore);
-
-    if (aAfterInitialization) {
-      // Force a reflow to our correct view manager size.
-      ForceResizeReflowWithCurrentDimensions();
-    }
   }
 
   if (mvmType) {
@@ -11270,32 +11342,33 @@ void PresShell::MaybeRecreateMobileViewportManager(bool aAfterInitialization) {
     // have one.
     MOZ_ASSERT(!mMobileViewportManager);
 
-    if (mPresContext->IsRootContentDocumentCrossProcess()) {
-      // Store the resolution so we can restore to this resolution when
-      // the MVM is destroyed.
-      mDocument->SetSavedResolutionBeforeMVM(mResolution.valueOr(1.0f));
-
-      mMVMContext = new GeckoMVMContext(mDocument, this);
-      mMobileViewportManager = new MobileViewportManager(mMVMContext, *mvmType);
-      if (MOZ_UNLIKELY(
-              MOZ_LOG_TEST(MobileViewportManager::gLog, LogLevel::Debug))) {
-        nsIURI* uri = mDocument->GetDocumentURI();
-        MOZ_LOG(MobileViewportManager::gLog, LogLevel::Debug,
-                ("Created MVM %p (type %d) for URI %s",
-                 mMobileViewportManager.get(), (int)*mvmType,
-                 uri ? uri->GetSpecOrDefault().get() : "(null)"));
-      }
-
-      if (aAfterInitialization) {
-        // Setting the initial viewport will trigger a reflow.
-        mMobileViewportManager->SetInitialViewport();
-      }
+    mMVMContext = new GeckoMVMContext(mDocument, this);
+    mMobileViewportManager = new MobileViewportManager(mMVMContext, *mvmType);
+    if (MOZ_UNLIKELY(
+            MOZ_LOG_TEST(MobileViewportManager::gLog, LogLevel::Debug))) {
+      nsIURI* uri = mDocument->GetDocumentURI();
+      MOZ_LOG(
+          MobileViewportManager::gLog, LogLevel::Debug,
+          ("Created MVM %p (type %d) for URI %s", mMobileViewportManager.get(),
+           (int)*mvmType, uri ? uri->GetSpecOrDefault().get() : "(null)"));
     }
   }
+  if (aAfterInitialization) {
+    // Setting the initial viewport will trigger a reflow.
+    if (mMobileViewportManager) {
+      mMobileViewportManager->SetInitialViewport();
+    } else {
+      // Force a reflow to our correct view manager size.
+      ForceResizeReflowWithCurrentDimensions();
+    }
+    // After we clear out the MVM and the MVMContext, also reset the
+    // resolution to 1.
+    SetResolutionAndScaleTo(1.0f, ResolutionChangeOrigin::MainThreadRestore);
+  }
 }
 
 bool PresShell::UsesMobileViewportSizing() const {
-  return mMobileViewportManager != nullptr &&
+  return mMobileViewportManager &&
          nsLayoutUtils::ShouldHandleMetaViewport(mDocument);
 }
 
@@ -11708,8 +11781,7 @@ static bool IsTopLevelWidget(nsIWidget* aWidget) {
 
   auto windowType = aWidget->GetWindowType();
   return windowType == WindowType::TopLevel ||
-         windowType == WindowType::Dialog || windowType == WindowType::Popup ||
-         windowType == WindowType::Sheet;
+         windowType == WindowType::Dialog || windowType == WindowType::Popup;
 }
 
 PresShell::WindowSizeConstraints PresShell::GetWindowSizeConstraints() {
diff --git a/layout/base/PresShell.h b/layout/base/PresShell.h
index 482ace1421..2b43b3c492 100644
--- a/layout/base/PresShell.h
+++ b/layout/base/PresShell.h
@@ -531,6 +531,12 @@ class PresShell final : public nsStubDocumentObserver,
                                 dom::HTMLSlotElement* aOldSlot,
                                 dom::HTMLSlotElement* aNewSlot);
 
+  /**
+   * Handles when a CustomStateSet state is about to be removed or added.
+   */
+  void CustomStatesWillChange(Element& aElement);
+  void CustomStateChanged(Element& aElement, nsAtom* aState);
+
   void PostRecreateFramesFor(Element*);
   void RestyleForAnimation(Element*, RestyleHint);
 
@@ -1604,6 +1610,18 @@ class PresShell final : public nsStubDocumentObserver,
   MOZ_CAN_RUN_SCRIPT nsresult ScrollToAnchor();
 
   /**
+   * Finds text fragments ranes in the document, highlights the ranges and
+   * scrolls to the last text fragment range on the page if
+   * `aScrollToTextFragment` is true.
+   *
+   * @param aScrollToTextFragment If true, scrolls the view to the last text
+   *                              fragment.
+   * @return True if scrolling happened.
+   */
+  MOZ_CAN_RUN_SCRIPT bool HighlightAndGoToTextFragment(
+      bool aScrollToTextFragment);
+
+  /**
    * When scroll anchoring adjusts positions in the root frame during page load,
    * it may move our scroll position in the root frame.
    *
diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index 8c07512093..81ffebf89a 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -2087,6 +2087,28 @@ void RestyleManager::AnimationsWithDestroyedFrame ::StopAnimationsWithoutFrame(
   }
 }
 
+// When using handled hints by an ancestor, we need to make sure that our
+// ancestor in the DOM tree is actually our ancestor in the flat tree.
+// Otherwise, we can't guarantee that e.g. a repaint from an ancestor in the DOM
+// will really end up repainting us.
+static bool CanUseHandledHintsFromAncestors(const nsIFrame* aFrame) {
+  if (aFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW)) {
+    // An out of flow can be parented in other part of the tree.
+    return false;
+  }
+  if (aFrame->IsColumnSpanInMulticolSubtree()) {
+    // Any column-spanner's parent frame is not its DOM parent's primary frame.
+    return false;
+  }
+  if (aFrame->IsTableCaption()) {
+    // This one is more subtle. captions are in-flow children of the table
+    // frame. But they are parented to the table wrapper. So hints handled for
+    // the inner table might not be applicable to us.
+    return false;
+  }
+  return true;
+}
+
 #ifdef DEBUG
 static bool IsAnonBox(const nsIFrame* aFrame) {
   return aFrame->Style()->IsAnonBox();
@@ -2185,8 +2207,7 @@ static bool IsInReplicatedFixedPosTree(const nsIFrame* aFrame) {
 
 void ServoRestyleState::AssertOwner(const ServoRestyleState& aParent) const {
   MOZ_ASSERT(mOwner);
-  MOZ_ASSERT(!mOwner->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW));
-  MOZ_ASSERT(!mOwner->IsColumnSpanInMulticolSubtree());
+  MOZ_ASSERT(CanUseHandledHintsFromAncestors(mOwner));
   // We allow aParent.mOwner to be null, for cases when we're not starting at
   // the root of the tree.  We also allow aParent.mOwner to be somewhere up our
   // expected owner chain not our immediate owner, which allows us creating long
@@ -2309,7 +2330,7 @@ size_t ServoRestyleState::ProcessMaybeNestedWrapperRestyle(nsIFrame* aParent,
       nsLayoutUtils::FirstContinuationOrIBSplitSibling(parent);
   if (parentForRestyle != aParent) {
     parentRestyleState.emplace(*parentForRestyle, *this, nsChangeHint_Empty,
-                               Type::InFlow);
+                               CanUseHandledHints::Yes);
   }
   ServoRestyleState& curRestyleState =
       parentRestyleState ? *parentRestyleState : *this;
@@ -2332,7 +2353,7 @@ size_t ServoRestyleState::ProcessMaybeNestedWrapperRestyle(nsIFrame* aParent,
       // the other hand, presumably our mChangesHandled already has the bits
       // we really want here so in practice it doesn't matter.
       ServoRestyleState childState(*cur, curRestyleState, nsChangeHint_Empty,
-                                   Type::InFlow,
+                                   CanUseHandledHints::Yes,
                                    /* aAssertWrapperRestyleLength = */ false);
       numProcessed +=
           childState.ProcessMaybeNestedWrapperRestyle(cur, aIndex + 1);
@@ -2652,8 +2673,7 @@ static void UpdateOneAdditionalComputedStyle(nsIFrame* aFrame, uint32_t aIndex,
   uint32_t equalStructs;  // Not used, actually.
   nsChangeHint childHint =
       aOldContext.CalcStyleDifference(*newStyle, &equalStructs);
-  if (!aFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW) &&
-      !aFrame->IsColumnSpanInMulticolSubtree()) {
+  if (CanUseHandledHintsFromAncestors(aFrame)) {
     childHint = NS_RemoveSubsumedHints(childHint,
                                        aRestyleState.ChangesHandledFor(aFrame));
   }
@@ -2812,11 +2832,8 @@ bool RestyleManager::ProcessPostTraversal(Element* aElement,
   const bool isOutOfFlow =
       primaryFrame && primaryFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW);
 
-  // We need this because any column-spanner's parent frame is not its DOM
-  // parent's primary frame. We need some special check similar to out-of-flow
-  // frames.
-  const bool isColumnSpan =
-      primaryFrame && primaryFrame->IsColumnSpanInMulticolSubtree();
+  const bool canUseHandledHints =
+      primaryFrame && CanUseHandledHintsFromAncestors(primaryFrame);
 
   // Grab the change hint from Servo.
   bool wasRestyled = false;
@@ -2848,11 +2865,12 @@ bool RestyleManager::ProcessPostTraversal(Element* aElement,
       maybeAnonBoxChild = primaryFrame->GetPlaceholderFrame();
     } else {
       maybeAnonBoxChild = primaryFrame;
-      // Do not subsume change hints for the column-spanner.
-      if (!isColumnSpan) {
-        changeHint = NS_RemoveSubsumedHints(
-            changeHint, aRestyleState.ChangesHandledFor(styleFrame));
-      }
+    }
+
+    // Do not subsume change hints for the column-spanner.
+    if (canUseHandledHints) {
+      changeHint = NS_RemoveSubsumedHints(
+          changeHint, aRestyleState.ChangesHandledFor(styleFrame));
     }
 
     // If the parent wasn't restyled, the styles of our anon box parents won't
@@ -2944,10 +2962,9 @@ bool RestyleManager::ProcessPostTraversal(Element* aElement,
 
   Maybe<ServoRestyleState> thisFrameRestyleState;
   if (styleFrame) {
-    auto type = isOutOfFlow || isColumnSpan ? ServoRestyleState::Type::OutOfFlow
-                                            : ServoRestyleState::Type::InFlow;
-
-    thisFrameRestyleState.emplace(*styleFrame, aRestyleState, changeHint, type);
+    thisFrameRestyleState.emplace(
+        *styleFrame, aRestyleState, changeHint,
+        ServoRestyleState::CanUseHandledHints(canUseHandledHints));
   }
 
   // We can't really assume as used changes from display: contents elements (or
@@ -3435,6 +3452,45 @@ void RestyleManager::ElementStateChanged(Element* aElement,
   MaybeRestyleForRelativeSelectorState(styleSet, aElement, aChangedBits);
 }
 
+void RestyleManager::CustomStatesWillChange(Element& aElement) {
+  MOZ_DIAGNOSTIC_ASSERT(!mInStyleRefresh);
+
+  IncrementUndisplayedRestyleGeneration();
+
+  // Relative selector invalidation travels ancestor and earlier sibling
+  // direction, so it's very possible that it invalidates a styled element.
+  if (!aElement.HasServoData() &&
+      !(aElement.GetSelectorFlags() &
+        NodeSelectorFlags::RelativeSelectorSearchDirectionAncestorSibling)) {
+    return;
+  }
+
+  ServoElementSnapshot& snapshot = SnapshotFor(aElement);
+  snapshot.AddCustomStates(aElement);
+}
+
+void RestyleManager::CustomStateChanged(Element& aElement, nsAtom* aState) {
+  ServoStyleSet& styleSet = *StyleSet();
+  MaybeRestyleForNthOfCustomState(styleSet, aElement, aState);
+  styleSet.MaybeInvalidateRelativeSelectorCustomStateDependency(
+      aElement, aState, Snapshots());
+}
+
+void RestyleManager::MaybeRestyleForNthOfCustomState(ServoStyleSet& aStyleSet,
+                                                     Element& aChild,
+                                                     nsAtom* aState) {
+  const auto* parentNode = aChild.GetParentNode();
+  MOZ_ASSERT(parentNode);
+  const auto parentFlags = parentNode->GetSelectorFlags();
+  if (!(parentFlags & NodeSelectorFlags::HasSlowSelectorNthOf)) {
+    return;
+  }
+
+  if (aStyleSet.HasNthOfCustomStateDependency(aChild, aState)) {
+    RestyleSiblingsForNthOf(&aChild, parentFlags);
+  }
+}
+
 void RestyleManager::MaybeRestyleForNthOfState(ServoStyleSet& aStyleSet,
                                                Element* aChild,
                                                ElementState aChangedBits) {
diff --git a/layout/base/RestyleManager.h b/layout/base/RestyleManager.h
index 62fef15a16..8485fe18a0 100644
--- a/layout/base/RestyleManager.h
+++ b/layout/base/RestyleManager.h
@@ -66,13 +66,11 @@ class ServoRestyleState {
   // our children too if we're out of flow since they aren't necessarily
   // parented in DOM order, and thus a change handled by a DOM ancestor doesn't
   // necessarily mean that it's handled for an ancestor frame.
-  enum class Type {
-    InFlow,
-    OutOfFlow,
-  };
+  enum class CanUseHandledHints : bool { No = false, Yes };
 
   ServoRestyleState(const nsIFrame& aOwner, ServoRestyleState& aParentState,
-                    nsChangeHint aHintForThisFrame, Type aType,
+                    nsChangeHint aHintForThisFrame,
+                    CanUseHandledHints aCanUseHandledHints,
                     bool aAssertWrapperRestyleLength = true)
       : mStyleSet(aParentState.mStyleSet),
         mChangeList(aParentState.mChangeList),
@@ -81,7 +79,7 @@ class ServoRestyleState {
             aParentState.mPendingScrollAnchorSuppressions),
         mPendingWrapperRestyleOffset(
             aParentState.mPendingWrapperRestyles.Length()),
-        mChangesHandled(aType == Type::InFlow
+        mChangesHandled(bool(aCanUseHandledHints)
                             ? aParentState.mChangesHandled | aHintForThisFrame
                             : aHintForThisFrame)
 #ifdef DEBUG
@@ -90,7 +88,7 @@ class ServoRestyleState {
         mAssertWrapperRestyleLength(aAssertWrapperRestyleLength)
 #endif
   {
-    if (aType == Type::InFlow) {
+    if (bool(aCanUseHandledHints)) {
       AssertOwner(aParentState);
     }
   }
@@ -361,6 +359,11 @@ class RestyleManager {
 
   void ElementStateChanged(Element*, dom::ElementState);
 
+  void CustomStatesWillChange(Element&);
+  void CustomStateChanged(Element&, nsAtom* aState);
+  void MaybeRestyleForNthOfCustomState(ServoStyleSet&, Element&,
+                                       nsAtom* aState);
+
   /**
    * Posts restyle hints for siblings of an element and their descendants if the
    * element's parent has NODE_HAS_SLOW_SELECTOR_NTH_OF and the element has a
diff --git a/layout/base/crashtests/crashtests.list b/layout/base/crashtests/crashtests.list
index d9cf87f4d2..3b1ed1e3d4 100644
--- a/layout/base/crashtests/crashtests.list
+++ b/layout/base/crashtests/crashtests.list
@@ -494,7 +494,7 @@ load 1463940.html
 HTTP load 1464641.html
 load 1464737.html
 load 1466638.html
-pref(layout.css.motion-path-ray.enabled,true) asserts(1-1) load 1467519.html # bogus size
+asserts(1-1) load 1467519.html # bogus size
 load 1467688.html
 load 1467964.html
 load 1469354.html
@@ -547,7 +547,7 @@ load 1599532.html
 pref(layout.accessiblecaret.enabled,true) load 1606492.html
 load 1654315.html
 load 1676301-1.html
-pref(apz.mvm.force-enabled,false) pref(dom.meta-viewport.enabled,false) pref(apz.allow_zooming,false) pref(layout.dynamic-toolbar-max-height,100) load 1689371.html
+pref(dom.meta-viewport.enabled,false) pref(apz.allow_zooming,false) pref(layout.dynamic-toolbar-max-height,100) load 1689371.html
 load 1685146.html
 load 1689912.html
 load 1690163.html
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 149f2f24bf..c0f35c278d 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -4985,9 +4985,8 @@ nsCSSFrameConstructor::FindSVGData(const Element& aElement,
   return data;
 }
 
-void nsCSSFrameConstructor::InsertPageBreakItem(
-    nsIContent* aContent, FrameConstructionItemList& aItems,
-    InsertPageBreakLocation location) {
+void nsCSSFrameConstructor::AppendPageBreakItem(
+    nsIContent* aContent, FrameConstructionItemList& aItems) {
   RefPtr<ComputedStyle> pseudoStyle =
       mPresShell->StyleSet()->ResolveNonInheritingAnonymousBoxStyle(
           PseudoStyleType::pageBreak);
@@ -4997,13 +4996,8 @@ void nsCSSFrameConstructor::InsertPageBreakItem(
 
   static constexpr FrameConstructionData sPageBreakData(NS_NewPageBreakFrame,
                                                         FCDATA_SKIP_FRAMESET);
-  if (location == InsertPageBreakLocation::eBefore) {
-    aItems.PrependItem(this, &sPageBreakData, aContent, pseudoStyle.forget(),
-                       true);
-  } else {
-    aItems.AppendItem(this, &sPageBreakData, aContent, pseudoStyle.forget(),
-                      true);
-  }
+  aItems.AppendItem(this, &sPageBreakData, aContent, pseudoStyle.forget(),
+                    true);
 }
 
 bool nsCSSFrameConstructor::ShouldCreateItemsForChild(
@@ -6012,7 +6006,7 @@ nsIFrame* nsCSSFrameConstructor::GetInsertionPrevSibling(
 
   // Find the frame that precedes the insertion point.
   FlattenedChildIterator iter(aInsertion->mContainer);
-  if (iter.ShadowDOMInvolved() || !aChild->IsRootOfNativeAnonymousSubtree()) {
+  if (!aChild->IsRootOfNativeAnonymousSubtree()) {
     // The check for IsRootOfNativeAnonymousSubtree() is because editor is
     // severely broken and calls us directly for native anonymous
     // nodes that it creates.
@@ -8390,7 +8384,7 @@ void nsCSSFrameConstructor::RecreateFramesForContent(
   }
 
   // TODO(emilio): We technically can find the right insertion point nowadays
-  // using StyleChildrenIterator rather than FlattenedTreeIterator. But we'd
+  // using StyleChildrenIterator rather than FlattenedChildIterator. But we'd
   // need to tweak the setup to insert into replaced elements to filter which
   // anonymous roots can be allowed, and which can't.
   //
diff --git a/layout/base/nsCSSFrameConstructor.h b/layout/base/nsCSSFrameConstructor.h
index 283d1385ce..51d5fe32d0 100644
--- a/layout/base/nsCSSFrameConstructor.h
+++ b/layout/base/nsCSSFrameConstructor.h
@@ -1423,18 +1423,8 @@ class nsCSSFrameConstructor final : public nsFrameManager {
   // for it.
   void ReframeTextIfNeeded(nsIContent* aContent);
 
-  enum InsertPageBreakLocation { eBefore, eAfter };
-  inline void AppendPageBreakItem(nsIContent* aContent,
-                                  FrameConstructionItemList& aItems) {
-    InsertPageBreakItem(aContent, aItems, InsertPageBreakLocation::eAfter);
-  }
-  inline void PrependPageBreakItem(nsIContent* aContent,
-                                   FrameConstructionItemList& aItems) {
-    InsertPageBreakItem(aContent, aItems, InsertPageBreakLocation::eBefore);
-  }
-  void InsertPageBreakItem(nsIContent* aContent,
-                           FrameConstructionItemList& aItems,
-                           InsertPageBreakLocation location);
+  void AppendPageBreakItem(nsIContent* aContent,
+                           FrameConstructionItemList& aItems);
 
   // Function to find FrameConstructionData for aElement.  Will return
   // null if aElement is not HTML.
diff --git a/layout/base/nsCaret.cpp b/layout/base/nsCaret.cpp
index d66d55d6bb..8707dcba5f 100644
--- a/layout/base/nsCaret.cpp
+++ b/layout/base/nsCaret.cpp
@@ -50,16 +50,7 @@ using BidiEmbeddingLevel = mozilla::intl::BidiEmbeddingLevel;
 // like an insignificant dot
 static const int32_t kMinBidiIndicatorPixels = 2;
 
-nsCaret::nsCaret()
-    : mOverrideOffset(0),
-      mBlinkCount(-1),
-      mBlinkRate(0),
-      mHideCount(0),
-      mIsBlinkOn(false),
-      mVisible(false),
-      mReadOnly(false),
-      mShowDuringSelection(false),
-      mIgnoreUserModify(true) {}
+nsCaret::nsCaret() = default;
 
 nsCaret::~nsCaret() { StopBlinking(); }
 
@@ -70,10 +61,6 @@ nsresult nsCaret::Init(PresShell* aPresShell) {
       do_GetWeakReference(aPresShell);  // the presshell owns us, so no addref
   NS_ASSERTION(mPresShell, "Hey, pres shell should support weak refs");
 
-  mShowDuringSelection =
-      LookAndFeel::GetInt(LookAndFeel::IntID::ShowCaretDuringSelection,
-                          mShowDuringSelection ? 1 : 0) != 0;
-
   RefPtr<Selection> selection =
       aPresShell->GetSelection(nsISelectionController::SELECTION_NORMAL);
   if (!selection) {
@@ -82,6 +69,7 @@ nsresult nsCaret::Init(PresShell* aPresShell) {
 
   selection->AddSelectionListener(this);
   mDomSelectionWeak = selection;
+  UpdateCaretPositionFromSelectionIfNeeded();
 
   return NS_OK;
 }
@@ -137,8 +125,7 @@ void nsCaret::Terminate() {
   }
   mDomSelectionWeak = nullptr;
   mPresShell = nullptr;
-
-  mOverrideContent = nullptr;
+  mCaretPosition = {};
 }
 
 NS_IMPL_ISUPPORTS(nsCaret, nsISelectionListener)
@@ -148,15 +135,30 @@ Selection* nsCaret::GetSelection() { return mDomSelectionWeak; }
 void nsCaret::SetSelection(Selection* aDOMSel) {
   MOZ_ASSERT(aDOMSel);
   mDomSelectionWeak = aDOMSel;
+  UpdateCaretPositionFromSelectionIfNeeded();
   ResetBlinking();
-  SchedulePaint(aDOMSel);
+  SchedulePaint();
 }
 
-void nsCaret::SetVisible(bool inMakeVisible) {
-  mVisible = inMakeVisible;
-  mIgnoreUserModify = mVisible;
+void nsCaret::SetVisible(bool aVisible) {
+  const bool wasVisible = mVisible;
+  mVisible = aVisible;
+  mIgnoreUserModify = aVisible;
+  if (mVisible != wasVisible) {
+    CaretVisibilityMaybeChanged();
+  }
+}
+
+bool nsCaret::IsVisible() const { return mVisible && !mHideCount; }
+
+void nsCaret::CaretVisibilityMaybeChanged() {
   ResetBlinking();
   SchedulePaint();
+  if (IsVisible()) {
+    // We ignore caret position updates when the caret is not visible, so we
+    // update the caret position here if needed.
+    UpdateCaretPositionFromSelectionIfNeeded();
+  }
 }
 
 void nsCaret::AddForceHide() {
@@ -164,20 +166,18 @@ void nsCaret::AddForceHide() {
   if (++mHideCount > 1) {
     return;
   }
-  ResetBlinking();
-  SchedulePaint();
+  CaretVisibilityMaybeChanged();
 }
 
 void nsCaret::RemoveForceHide() {
   if (!mHideCount || --mHideCount) {
     return;
   }
-  ResetBlinking();
-  SchedulePaint();
+  CaretVisibilityMaybeChanged();
 }
 
-void nsCaret::SetCaretReadOnly(bool inMakeReadonly) {
-  mReadOnly = inMakeReadonly;
+void nsCaret::SetCaretReadOnly(bool aReadOnly) {
+  mReadOnly = aReadOnly;
   ResetBlinking();
   SchedulePaint();
 }
@@ -333,61 +333,48 @@ nsRect nsCaret::GetGeometryForFrame(nsIFrame* aFrame, int32_t aFrameOffset,
   return rect;
 }
 
-nsIFrame* nsCaret::GetFrameAndOffset(const Selection* aSelection,
-                                     nsINode* aOverrideNode,
-                                     int32_t aOverrideOffset,
-                                     int32_t* aFrameOffset,
-                                     nsIFrame** aUnadjustedFrame) {
-  if (aUnadjustedFrame) {
-    *aUnadjustedFrame = nullptr;
+auto nsCaret::CaretPositionFor(const Selection* aSelection) -> CaretPosition {
+  if (!aSelection) {
+    return {};
   }
-
-  nsINode* focusNode;
-  int32_t focusOffset;
-
-  if (aOverrideNode) {
-    focusNode = aOverrideNode;
-    focusOffset = aOverrideOffset;
-  } else if (aSelection) {
-    focusNode = aSelection->GetFocusNode();
-    focusOffset = aSelection->FocusOffset();
-  } else {
-    return nullptr;
+  const nsFrameSelection* frameSelection = aSelection->GetFrameSelection();
+  if (!frameSelection) {
+    return {};
   }
+  nsINode* node = aSelection->GetFocusNode();
+  if (!node) {
+    return {};
+  }
+  return {
+      node,
+      int32_t(aSelection->FocusOffset()),
+      frameSelection->GetHint(),
+      frameSelection->GetCaretBidiLevel(),
+  };
+}
 
-  if (!focusNode || !focusNode->IsContent() || !aSelection) {
-    return nullptr;
+CaretFrameData nsCaret::GetFrameAndOffset(const CaretPosition& aPosition) {
+  nsINode* focusNode = aPosition.mContent;
+  int32_t focusOffset = aPosition.mOffset;
+
+  if (!focusNode || !focusNode->IsContent()) {
+    return {};
   }
 
   nsIContent* contentNode = focusNode->AsContent();
-  nsFrameSelection* frameSelection = aSelection->GetFrameSelection();
-  BidiEmbeddingLevel bidiLevel = frameSelection->GetCaretBidiLevel();
-  const CaretFrameData result =
-      SelectionMovementUtils::GetCaretFrameForNodeOffset(
-          frameSelection, contentNode, focusOffset, frameSelection->GetHint(),
-          bidiLevel, ForceEditableRegion::No);
-  // FIXME: It's odd to update nsFrameSelection within this method which is
-  // named as a getter.
-  if (result.mFrame) {
-    frameSelection->SetHint(result.mHint);
-  }
-  if (aUnadjustedFrame) {
-    *aUnadjustedFrame = result.mUnadjustedFrame;
-  }
-  if (aFrameOffset) {
-    *aFrameOffset = result.mOffsetInFrameContent;
-  }
-  return result.mFrame;
+  return SelectionMovementUtils::GetCaretFrameForNodeOffset(
+      nullptr, contentNode, focusOffset, aPosition.mHint, aPosition.mBidiLevel,
+      ForceEditableRegion::No);
 }
 
 /* static */
 nsIFrame* nsCaret::GetGeometry(const Selection* aSelection, nsRect* aRect) {
-  int32_t frameOffset;
-  nsIFrame* frame = GetFrameAndOffset(aSelection, nullptr, 0, &frameOffset);
-  if (frame) {
-    *aRect = GetGeometryForFrame(frame, frameOffset, nullptr);
+  auto data = GetFrameAndOffset(CaretPositionFor(aSelection));
+  if (data.mFrame) {
+    *aRect =
+        GetGeometryForFrame(data.mFrame, data.mOffsetInFrameContent, nullptr);
   }
-  return frame;
+  return data.mFrame;
 }
 
 [[nodiscard]] static nsIFrame* GetContainingBlockIfNeeded(nsIFrame* aFrame) {
@@ -397,39 +384,56 @@ nsIFrame* nsCaret::GetGeometry(const Selection* aSelection, nsRect* aRect) {
   return aFrame->GetContainingBlock();
 }
 
-void nsCaret::SchedulePaint(Selection* aSelection) {
-  Selection* selection;
-  if (aSelection) {
-    selection = aSelection;
-  } else {
-    selection = GetSelection();
+void nsCaret::SchedulePaint() {
+  if (mLastPaintedFrame) {
+    mLastPaintedFrame->SchedulePaint();
+    mLastPaintedFrame = nullptr;
   }
-
-  int32_t frameOffset;
-  nsIFrame* frame = GetFrameAndOffset(selection, mOverrideContent,
-                                      mOverrideOffset, &frameOffset);
-  if (!frame) {
+  auto data = GetFrameAndOffset(mCaretPosition);
+  if (!data.mFrame) {
     return;
   }
-
+  nsIFrame* frame = data.mFrame;
   if (nsIFrame* cb = GetContainingBlockIfNeeded(frame)) {
-    cb->SchedulePaint();
-  } else {
-    frame->SchedulePaint();
+    frame = cb;
   }
+  frame->SchedulePaint();
 }
 
 void nsCaret::SetVisibilityDuringSelection(bool aVisibility) {
+  if (mShowDuringSelection == aVisibility) {
+    return;
+  }
   mShowDuringSelection = aVisibility;
+  if (mHiddenDuringSelection && aVisibility) {
+    RemoveForceHide();
+    mHiddenDuringSelection = false;
+  }
   SchedulePaint();
 }
 
-void nsCaret::SetCaretPosition(nsINode* aNode, int32_t aOffset) {
-  mOverrideContent = aNode;
-  mOverrideOffset = aOffset;
+void nsCaret::UpdateCaretPositionFromSelectionIfNeeded() {
+  if (mFixedCaretPosition) {
+    return;
+  }
+  CaretPosition newPos = CaretPositionFor(GetSelection());
+  if (newPos == mCaretPosition) {
+    return;
+  }
+  mCaretPosition = newPos;
+  SchedulePaint();
+}
 
+void nsCaret::SetCaretPosition(nsINode* aNode, int32_t aOffset) {
+  // Schedule a paint with the old position to invalidate.
+  mFixedCaretPosition = !!aNode;
+  if (mFixedCaretPosition) {
+    mCaretPosition = {aNode, aOffset};
+    SchedulePaint();
+  } else {
+    UpdateCaretPositionFromSelectionIfNeeded();
+  }
   ResetBlinking();
-  SchedulePaint();
 }
 
 void nsCaret::CheckSelectionLanguageChange() {
@@ -478,16 +482,15 @@ nsIFrame* nsCaret::GetPaintGeometry(nsRect* aCaretRect, nsRect* aHookRect,
   // taken into account when computing the caret position below.
   CheckSelectionLanguageChange();
 
-  int32_t frameOffset;
-  nsIFrame* unadjustedFrame = nullptr;
-  nsIFrame* frame =
-      GetFrameAndOffset(GetSelection(), mOverrideContent, mOverrideOffset,
-                        &frameOffset, &unadjustedFrame);
-  MOZ_ASSERT(!!frame == !!unadjustedFrame);
-  if (!frame) {
+  auto data = GetFrameAndOffset(mCaretPosition);
+  MOZ_ASSERT(!!data.mFrame == !!data.mUnadjustedFrame);
+  if (!data.mFrame) {
     return nullptr;
   }
 
+  nsIFrame* frame = data.mFrame;
+  nsIFrame* unadjustedFrame = data.mUnadjustedFrame;
+  int32_t frameOffset(data.mOffsetInFrameContent);
   // Now we have a frame, check whether it's appropriate to show the caret here.
   // Note we need to check the unadjusted frame, otherwise consider the
   // following case:
@@ -555,26 +558,35 @@ void nsCaret::PaintCaret(DrawTarget& aDrawTarget, nsIFrame* aForFrame,
 NS_IMETHODIMP
 nsCaret::NotifySelectionChanged(Document*, Selection* aDomSel, int16_t aReason,
                                 int32_t aAmount) {
-  // Note that aDomSel, per the comment below may not be the same as our
-  // selection, but that's OK since if that is the case, it wouldn't have
-  // mattered what IsVisible() returns here, so we just opt for checking
-  // the selection later down below.
-  if ((aReason & nsISelectionListener::MOUSEUP_REASON) ||
-      !IsVisible(aDomSel))  // this wont do
-    return NS_OK;
-
   // The same caret is shared amongst the document and any text widgets it
   // may contain. This means that the caret could get notifications from
   // multiple selections.
   //
   // If this notification is for a selection that is not the one the
-  // the caret is currently interested in (mDomSelectionWeak), then there
-  // is nothing to do!
+  // the caret is currently interested in (mDomSelectionWeak), or the caret
+  // position is fixed, then there is nothing to do!
+  if (mDomSelectionWeak != aDomSel) {
+    return NS_OK;
+  }
 
-  if (mDomSelectionWeak != aDomSel) return NS_OK;
+  // Check if we need to hide / un-hide the caret due to the selection being
+  // collapsed.
+  if (!mShowDuringSelection &&
+      !aDomSel->IsCollapsed() != mHiddenDuringSelection) {
+    if (mHiddenDuringSelection) {
+      RemoveForceHide();
+    } else {
+      AddForceHide();
+    }
+    mHiddenDuringSelection = !mHiddenDuringSelection;
+  }
 
-  ResetBlinking();
-  SchedulePaint(aDomSel);
+  // We don't bother computing the caret position when invisible. We'll do it if
+  // we become visible in CaretVisibilityMaybeChanged().
+  if (IsVisible()) {
+    UpdateCaretPositionFromSelectionIfNeeded();
+    ResetBlinking();
+  }
 
   return NS_OK;
 }
@@ -589,7 +601,7 @@ void nsCaret::ResetBlinking() {
 
   mIsBlinkOn = true;
 
-  if (mReadOnly || !mVisible || mHideCount) {
+  if (mReadOnly || !IsVisible()) {
     StopBlinking();
     return;
   }
@@ -647,49 +659,6 @@ size_t nsCaret::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
   return total;
 }
 
-bool nsCaret::IsMenuPopupHidingCaret() {
-  // Check if there are open popups.
-  nsXULPopupManager* popMgr = nsXULPopupManager::GetInstance();
-  nsTArray<nsIFrame*> popups;
-  popMgr->GetVisiblePopups(popups);
-
-  if (popups.Length() == 0)
-    return false;  // No popups, so caret can't be hidden by them.
-
-  // Get the selection focus content, that's where the caret would
-  // go if it was drawn.
-  if (!mDomSelectionWeak) {
-    return true;  // No selection/caret to draw.
-  }
-  nsCOMPtr<nsIContent> caretContent =
-      nsIContent::FromNodeOrNull(mDomSelectionWeak->GetFocusNode());
-  if (!caretContent) return true;  // No selection/caret to draw.
-
-  // If there's a menu popup open before the popup with
-  // the caret, don't show the caret.
-  for (uint32_t i = 0; i < popups.Length(); i++) {
-    nsMenuPopupFrame* popupFrame = static_cast<nsMenuPopupFrame*>(popups[i]);
-    nsIContent* popupContent = popupFrame->GetContent();
-
-    if (caretContent->IsInclusiveDescendantOf(popupContent)) {
-      // The caret is in this popup. There were no menu popups before this
-      // popup, so don't hide the caret.
-      return false;
-    }
-
-    if (popupFrame->GetPopupType() == widget::PopupType::Menu &&
-        !popupFrame->IsContextMenu()) {
-      // This is an open menu popup. It does not contain the caret (else we'd
-      // have returned above). Even if the caret is in a subsequent popup,
-      // or another document/frame, it should be hidden.
-      return true;
-    }
-  }
-
-  // There are no open menu popups, no need to hide the caret.
-  return false;
-}
-
 void nsCaret::ComputeCaretRects(nsIFrame* aFrame, int32_t aFrameOffset,
                                 nsRect* aCaretRect, nsRect* aHookRect) {
   NS_ASSERTION(aFrame, "Should have a frame here");
diff --git a/layout/base/nsCaret.h b/layout/base/nsCaret.h
index 43329c827f..cba719962c 100644
--- a/layout/base/nsCaret.h
+++ b/layout/base/nsCaret.h
@@ -10,10 +10,10 @@
 #define nsCaret_h__
 
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/dom/Selection.h"
+#include "mozilla/SelectionMovementUtils.h"
 #include "nsCoord.h"
+#include "nsIFrame.h"
 #include "nsISelectionListener.h"
-#include "nsIWeakReferenceUtils.h"
 #include "nsPoint.h"
 #include "nsRect.h"
 
@@ -46,10 +46,10 @@ class nsCaret final : public nsISelectionListener {
 
   using CaretAssociationHint = mozilla::CaretAssociationHint;
 
-  nsresult Init(mozilla::PresShell* aPresShell);
+  nsresult Init(mozilla::PresShell*);
   void Terminate();
 
-  void SetSelection(mozilla::dom::Selection* aDOMSel);
+  void SetSelection(mozilla::dom::Selection*);
   mozilla::dom::Selection* GetSelection();
 
   /**
@@ -61,40 +61,18 @@ class nsCaret final : public nsISelectionListener {
    *                          those with user-modify: read-only
    */
   void SetIgnoreUserModify(bool aIgnoreUserModify);
-  /** SetVisible will set the visibility of the caret
-   *  @param inMakeVisible true to show the caret, false to hide it
+  /**
+   * SetVisible will set the visibility of the caret
+   *  @param aVisible true to show the caret, false to hide it
    */
-  void SetVisible(bool intMakeVisible);
-  /** IsVisible will get the visibility of the caret.
-   *  This returns false if the caret is hidden because it was set
-   *  to not be visible, or because the selection is not collapsed, or
-   *  because an open popup is hiding the caret.
-   *  It does not take account of blinking or the caret being hidden
-   *  because we're in non-editable/disabled content.
+  void SetVisible(bool aVisible);
+  /**
+   * IsVisible will get the visibility of the caret.
+   * It does not take account of blinking or the caret being hidden because
+   * we're in non-editable/disabled content.
    */
-  bool IsVisible(mozilla::dom::Selection* aSelection = nullptr) {
-    if (!mVisible || mHideCount) {
-      return false;
-    }
-
-    if (!mShowDuringSelection) {
-      mozilla::dom::Selection* selection;
-      if (aSelection) {
-        selection = aSelection;
-      } else {
-        selection = GetSelection();
-      }
-      if (!selection || !selection->IsCollapsed()) {
-        return false;
-      }
-    }
-
-    if (IsMenuPopupHidingCaret()) {
-      return false;
-    }
+  bool IsVisible() const;
 
-    return true;
-  }
   /**
    * AddForceHide() increases mHideCount and hide the caret even if
    * SetVisible(true) has been or will be called.  This is useful when the
@@ -114,7 +92,7 @@ class nsCaret final : public nsISelectionListener {
    *  @param inMakeReadonly true to show the caret in a 'read only' state,
    *         false to show the caret in normal, editing state
    */
-  void SetCaretReadOnly(bool inMakeReadonly);
+  void SetCaretReadOnly(bool aReadOnly);
   /**
    * @param aVisibility true if the caret should be visible even when the
    * selection is not collapsed.
@@ -132,7 +110,10 @@ class nsCaret final : public nsISelectionListener {
    * Schedule a repaint for the frame where the caret would appear.
    * Does not check visibility etc.
    */
-  void SchedulePaint(mozilla::dom::Selection* aSelection = nullptr);
+  void SchedulePaint();
+
+  nsIFrame* GetLastPaintedFrame() { return mLastPaintedFrame; }
+  void SetLastPaintedFrame(nsIFrame* aFrame) { mLastPaintedFrame = aFrame; }
 
   /**
    * Returns a frame to paint in, and the bounds of the painted caret
@@ -142,6 +123,7 @@ class nsCaret final : public nsISelectionListener {
    * off).
    */
   nsIFrame* GetPaintGeometry(nsRect* aRect);
+
   /**
    * Same as the overload above, but returns the caret and hook rects
    * separately, and also computes the color if requested.
@@ -165,6 +147,22 @@ class nsCaret final : public nsISelectionListener {
   // nsISelectionListener interface
   NS_DECL_NSISELECTIONLISTENER
 
+  /** The current caret position. */
+  struct CaretPosition {
+    nsCOMPtr<nsINode> mContent;
+    int32_t mOffset = 0;
+    CaretAssociationHint mHint{0};
+    mozilla::intl::BidiEmbeddingLevel mBidiLevel;
+
+    bool operator==(const CaretPosition& aOther) const {
+      return mContent == aOther.mContent && mOffset == aOther.mOffset &&
+             mHint == aOther.mHint && mBidiLevel == aOther.mBidiLevel;
+    }
+    explicit operator bool() const { return !!mContent; }
+  };
+
+  static CaretPosition CaretPositionFor(const mozilla::dom::Selection*);
+
   /**
    * Gets the position and size of the caret that would be drawn for
    * the focus node/offset of aSelection (assuming it would be drawn,
@@ -181,18 +179,9 @@ class nsCaret final : public nsISelectionListener {
   static nsRect GetGeometryForFrame(nsIFrame* aFrame, int32_t aFrameOffset,
                                     nscoord* aBidiIndicatorSize);
 
-  // Get the frame and frame offset based on the focus node and focus offset
-  // of aSelection. If aOverrideNode and aOverride are provided, use them
-  // instead.
-  // @param aFrameOffset return the frame offset if non-null.
-  // @param aUnadjustedFrame return the original frame that the selection is
-  // targeting, without any adjustment for painting.
-  // @return the frame of the focus node.
-  static nsIFrame* GetFrameAndOffset(const mozilla::dom::Selection* aSelection,
-                                     nsINode* aOverrideNode,
-                                     int32_t aOverrideOffset,
-                                     int32_t* aFrameOffset,
-                                     nsIFrame** aUnadjustedFrame = nullptr);
+  // Get the frame and frame offset based on aPosition.
+  static mozilla::CaretFrameData GetFrameAndOffset(
+      const CaretPosition& aPosition);
 
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 
@@ -200,6 +189,7 @@ class nsCaret final : public nsISelectionListener {
   static void CaretBlinkCallback(nsITimer* aTimer, void* aClosure);
 
   void CheckSelectionLanguageChange();
+  void CaretVisibilityMaybeChanged();
 
   void ResetBlinking();
   void StopBlinking();
@@ -213,72 +203,73 @@ class nsCaret final : public nsISelectionListener {
   void ComputeCaretRects(nsIFrame* aFrame, int32_t aFrameOffset,
                          nsRect* aCaretRect, nsRect* aHookRect);
 
-  // Returns true if we should not draw the caret because of XUL menu popups.
-  // The caret should be hidden if:
-  // 1. An open popup contains the caret, but a menu popup exists before the
-  //    caret-owning popup in the popup list (i.e. a menu is in front of the
-  //    popup with the caret). If the menu itself contains the caret we don't
-  //    hide it.
-  // 2. A menu popup is open, but there is no caret present in any popup.
-  // 3. The caret selection is empty.
-  bool IsMenuPopupHidingCaret();
+  // If we're tracking the selection, this updates the caret position and
+  // invalidates paint as needed.
+  void UpdateCaretPositionFromSelectionIfNeeded();
 
   nsWeakPtr mPresShell;
   mozilla::WeakPtr<mozilla::dom::Selection> mDomSelectionWeak;
 
   nsCOMPtr<nsITimer> mBlinkTimer;
 
-  /**
-   * The content to draw the caret at. If null, we use mDomSelectionWeak's
-   * focus node instead.
-   */
-  nsCOMPtr<nsINode> mOverrideContent;
-  /**
-   * The character offset to draw the caret at.
-   * Ignored if mOverrideContent is null.
-   */
-  int32_t mOverrideOffset;
+  CaretPosition mCaretPosition;
+
+  // The last frame we painted the caret in.
+  WeakFrame mLastPaintedFrame;
+
   /**
    * mBlinkCount is used to control the number of times to blink the caret
    * before stopping the blink. This is reset each time we reset the
    * blinking.
    */
-  int32_t mBlinkCount;
+  int32_t mBlinkCount = -1;
   /**
    * mBlinkRate is the rate of the caret blinking the last time we read it.
    * It is used as a way to optimize whether we need to reset the blinking
    * timer. 0 or a negative value means no blinking.
    */
-  int32_t mBlinkRate;
+  int32_t mBlinkRate = 0;
   /**
    * mHideCount is not 0, it means that somebody doesn't want the caret
    * to be visible.  See AddForceHide() and RemoveForceHide().
    */
-  uint32_t mHideCount;
+  uint32_t mHideCount = 0;
 
   /**
    * mIsBlinkOn is true when we're in a blink cycle where the caret is on.
    */
-  bool mIsBlinkOn;
+  bool mIsBlinkOn = false;
   /**
    * mIsVisible is true when SetVisible was last called with 'true'.
    */
-  bool mVisible;
+  bool mVisible = false;
   /**
    * mReadOnly is true when the caret is set to "read only" mode (i.e.,
    * it doesn't blink).
    */
-  bool mReadOnly;
+  bool mReadOnly = false;
   /**
    * mShowDuringSelection is true when the caret should be shown even when
    * the selection is not collapsed.
    */
-  bool mShowDuringSelection;
+  bool mShowDuringSelection = false;
   /**
    * mIgnoreUserModify is true when the caret should be shown even when
    * it's in non-user-modifiable content.
    */
-  bool mIgnoreUserModify;
+  bool mIgnoreUserModify = true;
+
+  /**
+   * If the caret position is fixed, it's been overridden externally and it
+   * will not track the selection.
+   */
+  bool mFixedCaretPosition = false;
+
+  /**
+   * If we're currently hiding the caret due to the selection not being
+   * collapsed. Can only be true if mShowDuringSelection is false.
+   */
+  bool mHiddenDuringSelection = false;
 };
 
 #endif  // nsCaret_h__
diff --git a/layout/base/nsCounterManager.cpp b/layout/base/nsCounterManager.cpp
index 7c2e9bb776..f2bbb5e50e 100644
--- a/layout/base/nsCounterManager.cpp
+++ b/layout/base/nsCounterManager.cpp
@@ -203,7 +203,11 @@ void nsCounterList::SetScope(nsCounterNode* aNode) {
   // the element itself, then we use that scope.
   // Otherwise, fall through to consider scopes created by siblings (and
   // their descendants) in reverse document order.
-  if (aNode->mType != nsCounterNode::USE &&
+  // Do this only for the list-item counter, while the CSSWG discusses what the
+  // right thing to do here is, see bug 1548753 and
+  // https://github.com/w3c/csswg-drafts/issues/5477.
+  if (mCounterName == nsGkAtoms::list_item &&
+      aNode->mType != nsCounterNode::USE &&
       StaticPrefs::layout_css_counter_ancestor_scope_enabled()) {
     for (auto* p = aNode->mPseudoFrame; p; p = p->GetParent()) {
       // This relies on the fact that a RESET node is always the first
diff --git a/layout/base/nsDocumentViewer.cpp b/layout/base/nsDocumentViewer.cpp
index d1cf9bf237..8ae0e001b8 100644
--- a/layout/base/nsDocumentViewer.cpp
+++ b/layout/base/nsDocumentViewer.cpp
@@ -449,6 +449,7 @@ class nsDocumentViewer final : public nsIDocumentViewer,
 
 #ifdef NS_PRINTING
   unsigned mClosingWhilePrinting : 1;
+  unsigned mCloseWindowAfterPrint : 1;
 
 #  if NS_PRINT_PREVIEW
   RefPtr<nsPrintJob> mPrintJob;
@@ -520,6 +521,7 @@ nsDocumentViewer::nsDocumentViewer()
       mInPermitUnloadPrompt(false),
 #ifdef NS_PRINTING
       mClosingWhilePrinting(false),
+      mCloseWindowAfterPrint(false),
 #endif  // NS_PRINTING
       mReloadEncodingSource(kCharsetUninitialized),
       mReloadEncoding(nullptr),
@@ -3140,6 +3142,20 @@ nsDocumentViewer::GetDoingPrintPreview(bool* aDoingPrintPreview) {
 }
 
 NS_IMETHODIMP
+nsDocumentViewer::GetCloseWindowAfterPrint(bool* aCloseWindowAfterPrint) {
+  NS_ENSURE_ARG_POINTER(aCloseWindowAfterPrint);
+
+  *aCloseWindowAfterPrint = mCloseWindowAfterPrint;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::SetCloseWindowAfterPrint(bool aCloseWindowAfterPrint) {
+  mCloseWindowAfterPrint = aCloseWindowAfterPrint;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
 nsDocumentViewer::ExitPrintPreview() {
   NS_ENSURE_TRUE(mPrintJob, NS_ERROR_FAILURE);
 
@@ -3301,15 +3317,23 @@ void nsDocumentViewer::OnDonePrinting() {
       printJob->Destroy();
     }
 
-    // We are done printing, now clean up.
-    //
-    // For non-print-preview jobs, we are actually responsible for cleaning up
-    // our whole <browser> or window (see the OPEN_PRINT_BROWSER code), so gotta
-    // run window.close(), which will take care of this.
-    //
-    // For print preview jobs the front-end code is responsible for cleaning the
-    // UI.
-    if (!printJob->CreatedForPrintPreview()) {
+// We are done printing, now clean up.
+//
+// If the original document to print was not a static clone, we opened a new
+// window and are responsible for cleaning up the whole <browser> or window
+// (see the OPEN_PRINT_BROWSER code, specifically
+// handleStaticCloneCreatedForPrint()), so gotta run window.close(), which
+// will take care of this.
+//
+// Otherwise the front-end code is responsible for cleaning the UI.
+#  ifdef ANDROID
+    // Android doesn't support Content Analysis and prints in a different way,
+    // so use different logic to clean up.
+    bool closeWindowAfterPrint = !printJob->CreatedForPrintPreview();
+#  else
+    bool closeWindowAfterPrint = GetCloseWindowAfterPrint();
+#  endif
+    if (closeWindowAfterPrint) {
       if (mContainer) {
         if (nsCOMPtr<nsPIDOMWindowOuter> win = mContainer->GetWindow()) {
           win->Close();
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index db766f6603..429ad335cc 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -714,12 +714,9 @@ bool nsLayoutUtils::AllowZoomingForDocument(
     return false;
   }
   // True if we allow zooming for all documents on this platform, or if we are
-  // in RDM and handling meta viewports, which force zoom under some
-  // circumstances.
-  BrowsingContext* bc = aDocument ? aDocument->GetBrowsingContext() : nullptr;
-  return StaticPrefs::apz_allow_zooming() ||
-         (bc && bc->InRDMPane() &&
-          nsLayoutUtils::ShouldHandleMetaViewport(aDocument));
+  // in RDM.
+  BrowsingContext* bc = aDocument->GetBrowsingContext();
+  return StaticPrefs::apz_allow_zooming() || (bc && bc->InRDMPane());
 }
 
 static bool HasVisibleAnonymousContents(Document* aDoc) {
@@ -4676,7 +4673,7 @@ nscoord nsLayoutUtils::IntrinsicForAxis(
       horizontalAxis ? stylePos->mMaxWidth : stylePos->mMaxHeight;
 
   PhysicalAxis ourInlineAxis =
-      aFrame->GetWritingMode().PhysicalAxis(eLogicalAxisInline);
+      aFrame->GetWritingMode().PhysicalAxis(LogicalAxis::Inline);
   const bool isInlineAxis = aAxis == ourInlineAxis;
 
   auto resetIfKeywords = [](StyleSize& aSize, StyleSize& aMinSize,
@@ -4897,8 +4894,8 @@ nscoord nsLayoutUtils::IntrinsicForAxis(
           // We are computing the size of |aFrame|, so we use the inline & block
           // dimensions of |aFrame|.
           result = ratio.ComputeRatioDependentSize(
-              isInlineAxis ? eLogicalAxisInline : eLogicalAxisBlock, childWM, h,
-              *contentBoxSizeToBoxSizingAdjust);
+              isInlineAxis ? LogicalAxis::Inline : LogicalAxis::Block, childWM,
+              h, *contentBoxSizeToBoxSizingAdjust);
           // We have get the inlineSizeForAspectRatio value, so we don't have to
           // recompute this again below.
           inlineSizeFromAspectRatio.emplace(result);
@@ -4910,8 +4907,8 @@ nscoord nsLayoutUtils::IntrinsicForAxis(
              GetPercentBSize(styleMaxBSize, aFrame, horizontalAxis, h))) {
           h = std::max(0, h - bSizeTakenByBoxSizing);
           nscoord maxISize = ratio.ComputeRatioDependentSize(
-              isInlineAxis ? eLogicalAxisInline : eLogicalAxisBlock, childWM, h,
-              *contentBoxSizeToBoxSizingAdjust);
+              isInlineAxis ? LogicalAxis::Inline : LogicalAxis::Block, childWM,
+              h, *contentBoxSizeToBoxSizingAdjust);
           if (maxISize < result) {
             result = maxISize;
           }
@@ -4926,8 +4923,8 @@ nscoord nsLayoutUtils::IntrinsicForAxis(
              GetPercentBSize(styleMinBSize, aFrame, horizontalAxis, h))) {
           h = std::max(0, h - bSizeTakenByBoxSizing);
           nscoord minISize = ratio.ComputeRatioDependentSize(
-              isInlineAxis ? eLogicalAxisInline : eLogicalAxisBlock, childWM, h,
-              *contentBoxSizeToBoxSizingAdjust);
+              isInlineAxis ? LogicalAxis::Inline : LogicalAxis::Block, childWM,
+              h, *contentBoxSizeToBoxSizingAdjust);
           if (minISize > result) {
             result = minISize;
           }
@@ -4990,9 +4987,9 @@ nscoord nsLayoutUtils::IntrinsicForAxis(
           GetDefiniteSizeTakenByBoxSizing(boxSizingForAR, aFrame, !isInlineAxis,
                                           ignorePadding, aPercentageBasis);
       bSize -= bSizeTakenByBoxSizing;
-      inlineSizeFromAspectRatio.emplace(ar.ComputeRatioDependentSize(
-          LogicalAxis::eLogicalAxisInline, childWM, bSize,
-          *contentBoxSizeToBoxSizingAdjust));
+      inlineSizeFromAspectRatio.emplace(
+          ar.ComputeRatioDependentSize(LogicalAxis::Inline, childWM, bSize,
+                                       *contentBoxSizeToBoxSizingAdjust));
     }
   }
 
@@ -5027,7 +5024,7 @@ nscoord nsLayoutUtils::IntrinsicForContainer(gfxContext* aRenderingContext,
   MOZ_ASSERT(aFrame && aFrame->GetParent());
   // We want the size aFrame will contribute to its parent's inline-size.
   PhysicalAxis axis =
-      aFrame->GetParent()->GetWritingMode().PhysicalAxis(eLogicalAxisInline);
+      aFrame->GetParent()->GetWritingMode().PhysicalAxis(LogicalAxis::Inline);
   return IntrinsicForAxis(axis, aRenderingContext, aFrame, aType, Nothing(),
                           aFlags);
 }
@@ -5056,7 +5053,7 @@ nscoord nsLayoutUtils::MinSizeContributionForAxis(
   StyleMaxSize maxSize =
       aAxis == eAxisHorizontal ? stylePos->mMaxWidth : stylePos->mMaxHeight;
   auto childWM = aFrame->GetWritingMode();
-  PhysicalAxis ourInlineAxis = childWM.PhysicalAxis(eLogicalAxisInline);
+  PhysicalAxis ourInlineAxis = childWM.PhysicalAxis(LogicalAxis::Inline);
   // According to the spec, max-content and min-content should behave as the
   // property's initial values in block axis.
   // It also make senses to use the initial values for -moz-fit-content and
@@ -5323,7 +5320,6 @@ nscoord nsLayoutUtils::MinISizeFromInline(nsIFrame* aFrame,
                "should not be container for font size inflation");
 
   nsIFrame::InlineMinISizeData data;
-  DISPLAY_MIN_INLINE_SIZE(aFrame, data.mPrevLines);
   aFrame->AddInlineMinISize(aRenderingContext, &data);
   data.ForceBreak();
   return data.mPrevLines;
@@ -5336,7 +5332,6 @@ nscoord nsLayoutUtils::PrefISizeFromInline(nsIFrame* aFrame,
                "should not be container for font size inflation");
 
   nsIFrame::InlinePrefISizeData data;
-  DISPLAY_PREF_INLINE_SIZE(aFrame, data.mPrevLines);
   aFrame->AddInlinePrefISize(aRenderingContext, &data);
   data.ForceBreak();
   return data.mPrevLines;
@@ -7449,7 +7444,7 @@ SurfaceFromElementResult nsLayoutUtils::SurfaceFromElement(
 
 SurfaceFromElementResult nsLayoutUtils::SurfaceFromElement(
     HTMLVideoElement* aElement, uint32_t aSurfaceFlags,
-    RefPtr<DrawTarget>& aTarget) {
+    RefPtr<DrawTarget>& aTarget, bool aOptimizeSourceSurface) {
   SurfaceFromElementResult result;
   result.mAlphaType = gfxAlphaType::Opaque;  // Assume opaque.
 
@@ -7484,7 +7479,7 @@ SurfaceFromElementResult nsLayoutUtils::SurfaceFromElement(
   result.mIsWriteOnly = CanvasUtils::CheckWriteOnlySecurity(
       result.mCORSUsed, result.mPrincipal, result.mHadCrossOriginRedirects);
 
-  if (aTarget) {
+  if (aTarget && aOptimizeSourceSurface) {
     // They gave us a DrawTarget to optimize for, so even though we have a
     // layers::Image, we should unconditionally try to grab a SourceSurface and
     // try to optimize it.
@@ -9769,24 +9764,8 @@ void nsLayoutUtils::ComputeSystemFont(nsFont* aSystemFont,
 
 /* static */
 bool nsLayoutUtils::ShouldHandleMetaViewport(const Document* aDocument) {
-  auto metaViewportOverride = nsIDocShell::META_VIEWPORT_OVERRIDE_NONE;
-  if (aDocument) {
-    if (nsIDocShell* docShell = aDocument->GetDocShell()) {
-      metaViewportOverride = docShell->GetMetaViewportOverride();
-    }
-  }
-  switch (metaViewportOverride) {
-    case nsIDocShell::META_VIEWPORT_OVERRIDE_ENABLED:
-      return true;
-    case nsIDocShell::META_VIEWPORT_OVERRIDE_DISABLED:
-      return false;
-    default:
-      MOZ_ASSERT(metaViewportOverride ==
-                 nsIDocShell::META_VIEWPORT_OVERRIDE_NONE);
-      // The META_VIEWPORT_OVERRIDE_NONE case means that there is no override
-      // and we rely solely on the StaticPrefs.
-      return StaticPrefs::dom_meta_viewport_enabled();
-  }
+  BrowsingContext* bc = aDocument->GetBrowsingContext();
+  return StaticPrefs::dom_meta_viewport_enabled() || (bc && bc->InRDMPane());
 }
 
 /* static */
diff --git a/layout/base/nsLayoutUtils.h b/layout/base/nsLayoutUtils.h
index 697b139ed9..135a9ad9ab 100644
--- a/layout/base/nsLayoutUtils.h
+++ b/layout/base/nsLayoutUtils.h
@@ -2230,7 +2230,7 @@ class nsLayoutUtils {
   }
   static mozilla::SurfaceFromElementResult SurfaceFromElement(
       mozilla::dom::HTMLVideoElement* aElement, uint32_t aSurfaceFlags,
-      RefPtr<DrawTarget>& aTarget);
+      RefPtr<DrawTarget>& aTarget, bool aOptimizeSourceSurface = true);
 
   /**
    * When the document is editable by contenteditable attribute of its root
diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index 7d9515c495..0786ec25d9 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -336,6 +336,7 @@ static const char* gExactCallbackPrefs[] = {
     "intl.accept_languages",
     "layout.css.devPixelsPerPx",
     "layout.css.dpi",
+    "layout.css.letter-spacing.model",
     "layout.css.text-transform.uppercase-eszett.enabled",
     "privacy.trackingprotection.enabled",
     "ui.use_standins_for_native_colors",
@@ -608,7 +609,8 @@ void nsPresContext::PreferenceChanged(const char* aPrefName) {
   }
 
   if (prefName.EqualsLiteral(
-          "layout.css.text-transform.uppercase-eszett.enabled")) {
+          "layout.css.text-transform.uppercase-eszett.enabled") ||
+      prefName.EqualsLiteral("layout.css.letter-spacing.model")) {
     changeHint |= NS_STYLE_HINT_REFLOW;
   }
 
@@ -1410,6 +1412,11 @@ void nsPresContext::SetInRDMPane(bool aInRDMPane) {
   }
   mInRDMPane = aInRDMPane;
   RecomputeTheme();
+  if (mPresShell) {
+    nsContentUtils::AddScriptRunner(NewRunnableMethod<bool>(
+        "PresShell::MaybeRecreateMobileViewportManager", mPresShell,
+        &PresShell::MaybeRecreateMobileViewportManager, true));
+  }
 }
 
 float nsPresContext::GetDeviceFullZoom() {
diff --git a/layout/base/nsRefreshDriver.cpp b/layout/base/nsRefreshDriver.cpp
index a5c2b1ded9..7885d6b8db 100644
--- a/layout/base/nsRefreshDriver.cpp
+++ b/layout/base/nsRefreshDriver.cpp
@@ -1528,6 +1528,16 @@ void nsRefreshDriver::PostScrollEvent(mozilla::Runnable* aScrollEvent,
   }
 }
 
+void nsRefreshDriver::PostScrollEndEvent(mozilla::Runnable* aScrollEndEvent,
+                                         bool aDelayed) {
+  if (aDelayed) {
+    mDelayedScrollEndEvents.AppendElement(aScrollEndEvent);
+  } else {
+    mScrollEndEvents.AppendElement(aScrollEndEvent);
+    EnsureTimerStarted();
+  }
+}
+
 void nsRefreshDriver::DispatchScrollEvents() {
   // Scroll events are one-shot, so after running them we can drop them.
   // However, dispatching a scroll event can potentially cause more scroll
@@ -1539,6 +1549,13 @@ void nsRefreshDriver::DispatchScrollEvents() {
   }
 }
 
+void nsRefreshDriver::DispatchScrollEndEvents() {
+  ScrollEventArray events = std::move(mScrollEndEvents);
+  for (auto& event : events) {
+    event->Run();
+  }
+}
+
 void nsRefreshDriver::PostVisualViewportScrollEvent(
     VVPScrollEvent* aScrollEvent) {
   mVisualViewportScrollEvents.AppendElement(aScrollEvent);
@@ -1673,6 +1690,9 @@ void nsRefreshDriver::RunDelayedEventsSoon() {
   mScrollEvents.AppendElements(mDelayedScrollEvents);
   mDelayedScrollEvents.Clear();
 
+  mScrollEndEvents.AppendElements(mDelayedScrollEvents);
+  mDelayedScrollEndEvents.Clear();
+
   mResizeEventFlushObservers.AppendElements(mDelayedResizeEventFlushObservers);
   mDelayedResizeEventFlushObservers.Clear();
 
@@ -2008,7 +2028,7 @@ auto nsRefreshDriver::GetReasonsToTick() const -> TickReasons {
   if (!mVisualViewportResizeEvents.IsEmpty()) {
     reasons |= TickReasons::eHasVisualViewportResizeEvents;
   }
-  if (!mScrollEvents.IsEmpty()) {
+  if (!mScrollEvents.IsEmpty() || !mScrollEndEvents.IsEmpty()) {
     reasons |= TickReasons::eHasScrollEvents;
   }
   if (!mVisualViewportScrollEvents.IsEmpty()) {
@@ -2476,6 +2496,7 @@ bool nsRefreshDriver::TickObserverArray(uint32_t aIdx, TimeStamp aNowTime) {
     FlushAutoFocusDocuments();
     DispatchScrollEvents();
     DispatchVisualViewportScrollEvents();
+    DispatchScrollEndEvents();
     EvaluateMediaQueriesAndReportChanges();
     DispatchAnimationEvents();
     RunFullscreenSteps();
diff --git a/layout/base/nsRefreshDriver.h b/layout/base/nsRefreshDriver.h
index cd050f7431..7bd0f883f4 100644
--- a/layout/base/nsRefreshDriver.h
+++ b/layout/base/nsRefreshDriver.h
@@ -114,7 +114,10 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   void DispatchVisualViewportResizeEvents();
 
   void PostScrollEvent(mozilla::Runnable* aScrollEvent, bool aDelayed = false);
+  void PostScrollEndEvent(mozilla::Runnable* aScrollEndEvent,
+                          bool aDelayed = false);
   void DispatchScrollEvents();
+  void DispatchScrollEndEvents();
 
   void PostVisualViewportScrollEvent(VVPScrollEvent* aScrollEvent);
   void DispatchVisualViewportScrollEvents();
@@ -694,10 +697,12 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   AutoTArray<nsCOMPtr<nsIRunnable>, 16> mEarlyRunners;
   VisualViewportResizeEventArray mVisualViewportResizeEvents;
   ScrollEventArray mScrollEvents;
+  ScrollEventArray mScrollEndEvents;
   VisualViewportScrollEventArray mVisualViewportScrollEvents;
 
   // Scroll events on documents that might have events suppressed.
   ScrollEventArray mDelayedScrollEvents;
+  ScrollEventArray mDelayedScrollEndEvents;
 
   AutoTArray<mozilla::PresShell*, 16> mResizeEventFlushObservers;
   AutoTArray<mozilla::PresShell*, 16> mDelayedResizeEventFlushObservers;
diff --git a/layout/base/tests/chrome/chrome.toml b/layout/base/tests/chrome/chrome.toml
index 6636b224e6..63e3da9609 100644
--- a/layout/base/tests/chrome/chrome.toml
+++ b/layout/base/tests/chrome/chrome.toml
@@ -66,6 +66,12 @@ support-files = [
   "printpreview_pps16_ref.html",
   "printpreview_prettyprint.xml",
   "printpreview_prettyprint_ref.xhtml",
+  "printpreview_scale_test_001.html",
+  "printpreview_scale_test_001_ref.html",
+  "printpreview_scale_test_002.html",
+  "printpreview_scale_test_002_ref.html",
+  "printpreview_scale_test_003.html",
+  "printpreview_scale_test_003_ref.html",
   "printpreview_mask.html",
   "print_page_size1.html",
   "print_page_size1_ref.html",
diff --git a/layout/base/tests/chrome/printpreview_helper.xhtml b/layout/base/tests/chrome/printpreview_helper.xhtml
index e40d2e4d5b..119c55d777 100644
--- a/layout/base/tests/chrome/printpreview_helper.xhtml
+++ b/layout/base/tests/chrome/printpreview_helper.xhtml
@@ -1708,9 +1708,252 @@ async function runTest58() {
   let test = "printpreview_mixed_page_size_002.html";
   // The params are just to give the file unique URLs.
   await compareFiles(test + "?test", test + "?ref");
+  requestAnimationFrame(() => setTimeout(runTest59));
+}
+
+// Creates a data URL that has a single div of |divSize| em square, on a page
+// of size |pageSize| inches square.
+// |center| determines if the div should be centered horizontally.
+function createScalingTestSource(pageSize, center, name) {
+  // Styling always used.
+  let baseStyle = 'background: blue;';
+  if (center) {
+    baseStyle += 'margin: auto;';
+  }
+  const div = '<div style="width: 100px; height: 100px;' + baseStyle + '"></div>';
+  const style = '<style>@page{size:' + pageSize + 'in}body{margin:0}</style>';
+  // Add the name as a comment, to ensure every test has a unique source even
+  // if the parameters are identical.
+  const comment = '<!-- ' + name + ' -->';
+  return 'data:text/html,' + style + div + comment;
+}
+
+async function runScalingCenteredTest(refPageSize, testPageSize, paperSize,
+    name, center = true, fuzz = null) {
+  const printSettings = {
+    settings: {
+      paperWidth: paperSize,
+      paperHeight: paperSize,
+      paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+      marginTop: 0,
+      marginRight: 0,
+      marginBottom: 0,
+      marginLeft: 0,
+      unwriteableMarginTop: 0,
+      unwriteableMarginRight: 0,
+      unwriteableMarginBottom: 0,
+      unwriteableMarginLeft: 0,
+    }
+  };
+  let settings = Object.create(fuzz, {
+    ref: {value: printSettings},
+    test: {value: printSettings}
+  });
+  const testSrc = createScalingTestSource(testPageSize, center, name);
+  const refSrc = createScalingTestSource(refPageSize, center, name);
+  return compareFiles(testSrc, refSrc, settings);
+}
+
+// Tests that auto-detection and use of page centering.
+// Has a smaller page on a larger sheet, where the difference is within the
+// tolerance for auto-detection.
+async function runTest59() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 2]]
+  });
+  // See bug 1680838
+  const fuzz = navigator.platform.includes("Win") ?
+      { maxDifferent: 180, maxDifference: 255 } :
+      null;
+  await runScalingCenteredTest(10, 9.5, 10, "runTest59", true, fuzz);
+  await SpecialPowers.popPrefEnv();
+  requestAnimationFrame(() => setTimeout(runTest60));
+}
+
+// Tests that centering won't occur when the pref disables it, using the same
+// values as runTest59.
+async function runTest60() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 0]]
+  });
+  // See bug 1680838
+  const fuzz = navigator.platform.includes("Win") ?
+      { maxDifferent: 180, maxDifference: 255 } :
+      null;
+  await runScalingCenteredTest(10, 9.5, 10, "runTest60", false, fuzz);
+  await SpecialPowers.popPrefEnv();
+  requestAnimationFrame(() => setTimeout(runTest61));
+}
+
+// Tests that auto-detection will reject too big a difference for page
+// centering. Has a much smaller page on a larger sheet, where the difference
+// is outside the threshold for auto-detection.
+async function runTest61() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 2]]
+  });
+  // See bug 1680838
+  const fuzz = navigator.platform.includes("Win") ?
+      { maxDifferent: 450, maxDifference: 255 } :
+      null;
+  await runScalingCenteredTest(10, 8.9, 10, "runTest61", false, fuzz);
+  await SpecialPowers.popPrefEnv();
+  requestAnimationFrame(() => setTimeout(runTest62));
+}
+
+// Tests that we can force page centering with the pref, using the same values
+// as runTest61.
+async function runTest62() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 1]]
+  });
+  // See bug 1680838
+  const fuzz = navigator.platform.includes("Win") ?
+      { maxDifferent: 450, maxDifference: 255 } :
+      null;
+  await runScalingCenteredTest(10, 8.9, 10, "runTest62", true, fuzz);
+  await SpecialPowers.popPrefEnv();
+  requestAnimationFrame(() => setTimeout(runTest63));
+}
+
+// Tests that centering will always happen if the pref forces it.
+// The sizes used in these files are very large and the scale factor very high
+// here to ensure that any errors in the calculation for centering will be
+// magnified.
+async function runTest63() {
+  let test = "printpreview_scale_test_001.html";
+  let ref = "printpreview_scale_test_001_ref.html";
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 1]]
+  });
+  await compareFiles(test, ref, {
+    test: {
+      settings: {
+        paperWidth: 8.5,
+        paperHeight: 11,
+        paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+        marginTop: 0,
+        marginRight: 0,
+        marginBottom: 0,
+        marginLeft: 0,
+        unwriteableMarginTop: 0,
+        unwriteableMarginRight: 0,
+        unwriteableMarginBottom: 0,
+        unwriteableMarginLeft: 0,
+      },
+    },
+    ref: {
+      settings: {
+        paperWidth: 8.5,
+        paperHeight: 11,
+        paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+        marginTop: 0,
+        marginRight: 0,
+        marginBottom: 0,
+        marginLeft: 0,
+        unwriteableMarginTop: 0,
+        unwriteableMarginRight: 0,
+        unwriteableMarginBottom: 0,
+        unwriteableMarginLeft: 0,
+      },
+    },
+  });
+  await SpecialPowers.popPrefEnv();
+  requestAnimationFrame(() => setTimeout(runTest64));
+}
+
+// Tests that printing A4 pages on US Letter will be a close enough fit
+// that we will automatically center the page.
+async function runTest64() {
+  let test = "printpreview_scale_test_002.html";
+  let ref = "printpreview_scale_test_002_ref.html";
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 2]]
+  });
+  await compareFiles(test, ref, {
+    test: {
+      settings: {
+        paperWidth: 8.5,
+        paperHeight: 11,
+        paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+        marginTop: 0,
+        marginRight: 0,
+        marginBottom: 0,
+        marginLeft: 0,
+        unwriteableMarginTop: 0,
+        unwriteableMarginRight: 0,
+        unwriteableMarginBottom: 0,
+        unwriteableMarginLeft: 0,
+      },
+    },
+    ref: {
+      settings: {
+        paperWidth: 8.5,
+        paperHeight: 11,
+        paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+        marginTop: 0,
+        marginRight: 0,
+        marginBottom: 0,
+        marginLeft: 0,
+        unwriteableMarginTop: 0,
+        unwriteableMarginRight: 0,
+        unwriteableMarginBottom: 0,
+        unwriteableMarginLeft: 0,
+      },
+    },
+  });
+  await SpecialPowers.popPrefEnv();
+  requestAnimationFrame(() => setTimeout(runTest65));
+}
+
+// Tests that auto-detection will reject a large enough difference in width
+// when downscaling is used to make the page fit on the paper.
+async function runTest65() {
+  let test = "printpreview_scale_test_003.html";
+  let ref = "printpreview_scale_test_003_ref.html";
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.center_page_on_sheet", 2]]
+  });
+  await compareFiles(test, ref, {
+    test: {
+      settings: {
+        paperWidth: 8.5,
+        paperHeight: 11,
+        paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+        marginTop: 0,
+        marginRight: 0,
+        marginBottom: 0,
+        marginLeft: 0,
+        unwriteableMarginTop: 0,
+        unwriteableMarginRight: 0,
+        unwriteableMarginBottom: 0,
+        unwriteableMarginLeft: 0,
+      },
+    },
+    ref: {
+      settings: {
+        paperWidth: 8.5,
+        paperHeight: 11,
+        paperSizeUnit: Ci.nsIPrintSettings.kPaperSizeInches,
+        marginTop: 0,
+        marginRight: 0,
+        marginBottom: 0,
+        marginLeft: 0,
+        unwriteableMarginTop: 0,
+        unwriteableMarginRight: 0,
+        unwriteableMarginBottom: 0,
+        unwriteableMarginLeft: 0,
+      },
+    },
+  });
+  await SpecialPowers.popPrefEnv();
   finish();
 }
 
+
 ]]></script>
 <table style="border: 1px solid black;" xmlns="http://www.w3.org/1999/xhtml">
 <tr><th>Print preview canvas 1</th><th>Print preview canvas 2</th></tr>
diff --git a/layout/base/tests/chrome/printpreview_scale_test_001.html b/layout/base/tests/chrome/printpreview_scale_test_001.html
new file mode 100644
index 0000000000..e9d3122b6b
--- /dev/null
+++ b/layout/base/tests/chrome/printpreview_scale_test_001.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<head>
+  <style>
+@page {
+  size: 10in 22in;
+  margin: 0;
+}
+body{
+  margin:0;
+}
+div{
+  width: 2in;
+  height: 2in;
+  background: blue;
+  margin-left: 4in;
+}
+  </style>
+</head>
+<body>
+  <div></div>
+</body>
diff --git a/layout/base/tests/chrome/printpreview_scale_test_001_ref.html b/layout/base/tests/chrome/printpreview_scale_test_001_ref.html
new file mode 100644
index 0000000000..2ed4571ef1
--- /dev/null
+++ b/layout/base/tests/chrome/printpreview_scale_test_001_ref.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<head>
+  <style>
+@page {
+  size: 4in 44in;
+  margin: 0;
+}
+body{
+  margin:0;
+}
+div{
+  height: 4in;
+  width: 4in;
+  background: blue;
+}
+  </style>
+</head>
+<body>
+  <div></div>
+</body>
diff --git a/layout/base/tests/chrome/printpreview_scale_test_002.html b/layout/base/tests/chrome/printpreview_scale_test_002.html
new file mode 100644
index 0000000000..94c35ab3c3
--- /dev/null
+++ b/layout/base/tests/chrome/printpreview_scale_test_002.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<head>
+  <style>
+@page {
+  size: A4;
+  margin: 0;
+}
+body{
+  margin:0;
+}
+div{
+  height: 200px;
+  width: 200px;
+  background: blue;
+  margin: auto;
+}
+  </style>
+</head>
+<body>
+  <div></div>
+</body>
diff --git a/layout/base/tests/chrome/printpreview_scale_test_002_ref.html b/layout/base/tests/chrome/printpreview_scale_test_002_ref.html
new file mode 100644
index 0000000000..d73de86fe5
--- /dev/null
+++ b/layout/base/tests/chrome/printpreview_scale_test_002_ref.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<head>
+  <style>
+@page {
+  size: letter;
+  margin: 0;
+}
+body{
+  margin:0;
+}
+div{
+  /* A4-on-letter requires a 0.9407 downscale. 11in = 279.4mm, and
+   * 279.4mm / 297mm = 0.9407407407..
+   * The unscaled reference case has a 200px square div, so reverse the scale
+   * to match that (rounding to 0.940741)
+   */
+  height: calc(0.940741 * 200px);
+  width: calc(0.940741 * 200px);
+  background: blue;
+  margin: auto;
+}
+  </style>
+</head>
+<body>
+  <div></div>
+</body>
diff --git a/layout/base/tests/chrome/printpreview_scale_test_003.html b/layout/base/tests/chrome/printpreview_scale_test_003.html
new file mode 100644
index 0000000000..2b1d68ff60
--- /dev/null
+++ b/layout/base/tests/chrome/printpreview_scale_test_003.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<head>
+  <style>
+@page {
+  size: 8.5in 13in;
+  margin: 0;
+}
+body{
+  margin:0;
+}
+div{
+  /* 13in / 11in = 1.1818181... */
+  height: calc(1.1818182 * 200px);
+  width: calc(1.1818182 * 200px);
+  background: blue;
+}
+  </style>
+</head>
+<body>
+  <div></div>
+</body>
diff --git a/layout/base/tests/chrome/printpreview_scale_test_003_ref.html b/layout/base/tests/chrome/printpreview_scale_test_003_ref.html
new file mode 100644
index 0000000000..41a3f87889
--- /dev/null
+++ b/layout/base/tests/chrome/printpreview_scale_test_003_ref.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<head>
+  <style>
+@page {
+  size: 8.5in 11in;
+  margin: 0;
+}
+body{
+  margin:0;
+}
+div{
+  /* 11in / 13in = 0.8461538 */
+  height: 200px;
+  width: 200px;
+  background: blue;
+}
+  </style>
+</head>
+<body>
+  <div></div>
+</body>
diff --git a/layout/base/tests/chrome/test_bug420499.xhtml b/layout/base/tests/chrome/test_bug420499.xhtml
index 22fefd7987..8db69ff6c1 100644
--- a/layout/base/tests/chrome/test_bug420499.xhtml
+++ b/layout/base/tests/chrome/test_bug420499.xhtml
@@ -84,7 +84,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=420499
 
     function popupMenuShownHandler() {
       window.removeEventListener("popupshown", popupMenuShownHandler);
-      ok(!isCaretVisible(), "Caret shouldn't be visible when menu open");
+      ok(isCaretVisible(), "Caret shouldn't be visible when menu open");
       window.addEventListener("popuphidden", ensureParagraphFocused);
       $("menu").open = false;
     }
diff --git a/layout/build/nsLayoutStatics.cpp b/layout/build/nsLayoutStatics.cpp
index 1738098ed2..ecc84ad286 100644
--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -183,9 +183,6 @@ nsresult nsLayoutStatics::Initialize() {
 
   nsMathMLOperators::AddRefTable();
 
-#ifdef DEBUG
-  nsIFrame::DisplayReflowStartup();
-#endif
   Attr::Initialize();
 
   PopupBlocker::Initialize();
@@ -320,9 +317,6 @@ void nsLayoutStatics::Shutdown() {
   HTMLDNSPrefetch::Shutdown();
   nsCSSRendering::Shutdown();
   StaticPresData::Shutdown();
-#ifdef DEBUG
-  nsIFrame::DisplayReflowShutdown();
-#endif
   nsCellMap::Shutdown();
   ActiveLayerTracker::Shutdown();
 
diff --git a/layout/forms/nsCheckboxRadioFrame.cpp b/layout/forms/nsCheckboxRadioFrame.cpp
index e2b8541613..4bf15099aa 100644
--- a/layout/forms/nsCheckboxRadioFrame.cpp
+++ b/layout/forms/nsCheckboxRadioFrame.cpp
@@ -52,18 +52,12 @@ void nsCheckboxRadioFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
 
 /* virtual */
 nscoord nsCheckboxRadioFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  result = StyleDisplay()->HasAppearance() ? DefaultSize() : 0;
-  return result;
+  return StyleDisplay()->HasAppearance() ? DefaultSize() : 0;
 }
 
 /* virtual */
 nscoord nsCheckboxRadioFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  result = StyleDisplay()->HasAppearance() ? DefaultSize() : 0;
-  return result;
+  return StyleDisplay()->HasAppearance() ? DefaultSize() : 0;
 }
 
 /* virtual */
@@ -76,13 +70,9 @@ LogicalSize nsCheckboxRadioFrame::ComputeAutoSize(
   if (!StyleDisplay()->HasAppearance()) {
     return size;
   }
-
-  // Note: this call always set the BSize to NS_UNCONSTRAINEDSIZE.
-  size = nsAtomicContainerFrame::ComputeAutoSize(
+  return nsAtomicContainerFrame::ComputeAutoSize(
       aRC, aWM, aCBSize, aAvailableISize, aMargin, aBorderPadding,
       aSizeOverrides, aFlags);
-  size.BSize(aWM) = DefaultSize();
-  return size;
 }
 
 Maybe<nscoord> nsCheckboxRadioFrame::GetNaturalBaselineBOffset(
@@ -125,7 +115,6 @@ void nsCheckboxRadioFrame::Reflow(nsPresContext* aPresContext,
                                   nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsCheckboxRadioFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
@@ -133,10 +122,13 @@ void nsCheckboxRadioFrame::Reflow(nsPresContext* aPresContext,
        aReflowInput.AvailableWidth(), aReflowInput.AvailableHeight()));
 
   const auto wm = aReflowInput.GetWritingMode();
-  aDesiredSize.SetSize(wm, aReflowInput.ComputedSizeWithBorderPadding(wm));
-
+  const auto contentBoxSize =
+      aReflowInput.ComputedSizeWithBSizeFallback([&] { return DefaultSize(); });
+  aDesiredSize.SetSize(
+      wm,
+      contentBoxSize + aReflowInput.ComputedLogicalBorderPadding(wm).Size(wm));
   if (nsLayoutUtils::FontSizeInflationEnabled(aPresContext)) {
-    float inflation = nsLayoutUtils::FontSizeInflationFor(this);
+    const float inflation = nsLayoutUtils::FontSizeInflationFor(this);
     aDesiredSize.Width() *= inflation;
     aDesiredSize.Height() *= inflation;
   }
diff --git a/layout/forms/nsComboboxControlFrame.cpp b/layout/forms/nsComboboxControlFrame.cpp
index 1d4ff15b4f..98486255d0 100644
--- a/layout/forms/nsComboboxControlFrame.cpp
+++ b/layout/forms/nsComboboxControlFrame.cpp
@@ -190,14 +190,12 @@ nscoord nsComboboxControlFrame::GetIntrinsicISize(gfxContext* aRenderingContext,
 
 nscoord nsComboboxControlFrame::GetMinISize(gfxContext* aRenderingContext) {
   nscoord minISize;
-  DISPLAY_MIN_INLINE_SIZE(this, minISize);
   minISize = GetIntrinsicISize(aRenderingContext, IntrinsicISizeType::MinISize);
   return minISize;
 }
 
 nscoord nsComboboxControlFrame::GetPrefISize(gfxContext* aRenderingContext) {
   nscoord prefISize;
-  DISPLAY_PREF_INLINE_SIZE(this, prefISize);
   prefISize =
       GetIntrinsicISize(aRenderingContext, IntrinsicISizeType::PrefISize);
   return prefISize;
diff --git a/layout/forms/nsDateTimeControlFrame.cpp b/layout/forms/nsDateTimeControlFrame.cpp
index b19f787dbc..d8cdf5f277 100644
--- a/layout/forms/nsDateTimeControlFrame.cpp
+++ b/layout/forms/nsDateTimeControlFrame.cpp
@@ -35,33 +35,21 @@ nsDateTimeControlFrame::nsDateTimeControlFrame(ComputedStyle* aStyle,
     : nsContainerFrame(aStyle, aPresContext, kClassID) {}
 
 nscoord nsDateTimeControlFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-
   nsIFrame* kid = mFrames.FirstChild();
-  if (kid) {  // display:none?
-    result = nsLayoutUtils::IntrinsicForContainer(aRenderingContext, kid,
-                                                  IntrinsicISizeType::MinISize);
-  } else {
-    result = 0;
+  if (!kid) {
+    return 0;
   }
-
-  return result;
+  return nsLayoutUtils::IntrinsicForContainer(aRenderingContext, kid,
+                                              IntrinsicISizeType::MinISize);
 }
 
 nscoord nsDateTimeControlFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
   nsIFrame* kid = mFrames.FirstChild();
-  if (kid) {  // display:none?
-    result = nsLayoutUtils::IntrinsicForContainer(
-        aRenderingContext, kid, IntrinsicISizeType::PrefISize);
-  } else {
-    result = 0;
+  if (!kid) {
+    return 0;
   }
-
-  return result;
+  return nsLayoutUtils::IntrinsicForContainer(aRenderingContext, kid,
+                                              IntrinsicISizeType::PrefISize);
 }
 
 Maybe<nscoord> nsDateTimeControlFrame::GetNaturalBaselineBOffset(
@@ -78,7 +66,6 @@ void nsDateTimeControlFrame::Reflow(nsPresContext* aPresContext,
   MarkInReflow();
 
   DO_GLOBAL_REFLOW_COUNT("nsDateTimeControlFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
diff --git a/layout/forms/nsFieldSetFrame.cpp b/layout/forms/nsFieldSetFrame.cpp
index c96b293e82..2648cb4dd3 100644
--- a/layout/forms/nsFieldSetFrame.cpp
+++ b/layout/forms/nsFieldSetFrame.cpp
@@ -58,7 +58,7 @@ nsRect nsFieldSetFrame::VisualBorderRectRelativeToSelf() const {
     auto legendMargin = legend->GetLogicalUsedMargin(wm);
     nscoord legendStartMargin = legendMargin.BStart(wm);
     nscoord legendEndMargin = legendMargin.BEnd(wm);
-    nscoord border = GetUsedBorder().Side(wm.PhysicalSide(eLogicalSideBStart));
+    nscoord border = GetUsedBorder().Side(wm.PhysicalSide(LogicalSide::BStart));
     // Calculate the offset from the border area block-axis start edge needed to
     // center-align our border with the legend's border-box (in the block-axis).
     nscoord off = (legendStartMargin + legendSize / 2) - border / 2;
@@ -348,19 +348,11 @@ nscoord nsFieldSetFrame::GetIntrinsicISize(gfxContext* aRenderingContext,
 }
 
 nscoord nsFieldSetFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-
-  result = GetIntrinsicISize(aRenderingContext, IntrinsicISizeType::MinISize);
-  return result;
+  return GetIntrinsicISize(aRenderingContext, IntrinsicISizeType::MinISize);
 }
 
 nscoord nsFieldSetFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
-  result = GetIntrinsicISize(aRenderingContext, IntrinsicISizeType::PrefISize);
-  return result;
+  return GetIntrinsicISize(aRenderingContext, IntrinsicISizeType::PrefISize);
 }
 
 /* virtual */
@@ -372,7 +364,6 @@ void nsFieldSetFrame::Reflow(nsPresContext* aPresContext,
 
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsFieldSetFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_WARNING_ASSERTION(aReflowInput.ComputedISize() != NS_UNCONSTRAINEDSIZE,
                        "Should have a precomputed inline-size!");
diff --git a/layout/forms/nsHTMLButtonControlFrame.cpp b/layout/forms/nsHTMLButtonControlFrame.cpp
index cb24ccbfb9..5201e420e2 100644
--- a/layout/forms/nsHTMLButtonControlFrame.cpp
+++ b/layout/forms/nsHTMLButtonControlFrame.cpp
@@ -51,6 +51,7 @@ void nsHTMLButtonControlFrame::Init(nsIContent* aContent,
 }
 
 NS_QUERYFRAME_HEAD(nsHTMLButtonControlFrame)
+  NS_QUERYFRAME_ENTRY(nsHTMLButtonControlFrame)
   NS_QUERYFRAME_ENTRY(nsIFormControlFrame)
 NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
 
@@ -238,29 +239,21 @@ void nsHTMLButtonControlFrame::BuildDisplayList(
 }
 
 nscoord nsHTMLButtonControlFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
   if (Maybe<nscoord> containISize = ContainIntrinsicISize()) {
-    result = *containISize;
-  } else {
-    nsIFrame* kid = mFrames.FirstChild();
-    result = nsLayoutUtils::IntrinsicForContainer(aRenderingContext, kid,
-                                                  IntrinsicISizeType::MinISize);
+    return *containISize;
   }
-  return result;
+  nsIFrame* kid = mFrames.FirstChild();
+  return nsLayoutUtils::IntrinsicForContainer(aRenderingContext, kid,
+                                              IntrinsicISizeType::MinISize);
 }
 
 nscoord nsHTMLButtonControlFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
   if (Maybe<nscoord> containISize = ContainIntrinsicISize()) {
-    result = *containISize;
-  } else {
-    nsIFrame* kid = mFrames.FirstChild();
-    result = nsLayoutUtils::IntrinsicForContainer(
-        aRenderingContext, kid, IntrinsicISizeType::PrefISize);
+    return *containISize;
   }
-  return result;
+  nsIFrame* kid = mFrames.FirstChild();
+  return nsLayoutUtils::IntrinsicForContainer(aRenderingContext, kid,
+                                              IntrinsicISizeType::PrefISize);
 }
 
 void nsHTMLButtonControlFrame::Reflow(nsPresContext* aPresContext,
@@ -269,7 +262,6 @@ void nsHTMLButtonControlFrame::Reflow(nsPresContext* aPresContext,
                                       nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsHTMLButtonControlFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Reflow the child
diff --git a/layout/forms/nsImageControlFrame.cpp b/layout/forms/nsImageControlFrame.cpp
index 17e3893a2f..8207a427f1 100644
--- a/layout/forms/nsImageControlFrame.cpp
+++ b/layout/forms/nsImageControlFrame.cpp
@@ -97,7 +97,6 @@ void nsImageControlFrame::Reflow(nsPresContext* aPresContext,
                                  const ReflowInput& aReflowInput,
                                  nsReflowStatus& aStatus) {
   DO_GLOBAL_REFLOW_COUNT("nsImageControlFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   return nsImageFrame::Reflow(aPresContext, aDesiredSize, aReflowInput,
                               aStatus);
diff --git a/layout/forms/nsListControlFrame.cpp b/layout/forms/nsListControlFrame.cpp
index 44ce9fde13..3020e99888 100644
--- a/layout/forms/nsListControlFrame.cpp
+++ b/layout/forms/nsListControlFrame.cpp
@@ -230,34 +230,30 @@ nscoord nsListControlFrame::CalcBSizeOfARow() {
 }
 
 nscoord nsListControlFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
   // Always add scrollbar inline sizes to the pref-inline-size of the
   // scrolled content. Combobox frames depend on this happening in the
   // dropdown, and standalone listboxes are overflow:scroll so they need
   // it too.
   WritingMode wm = GetWritingMode();
   Maybe<nscoord> containISize = ContainIntrinsicISize();
-  result = containISize ? *containISize
-                        : GetScrolledFrame()->GetPrefISize(aRenderingContext);
+  nscoord result = containISize
+                       ? *containISize
+                       : GetScrolledFrame()->GetPrefISize(aRenderingContext);
   LogicalMargin scrollbarSize(wm, GetDesiredScrollbarSizes());
   result = NSCoordSaturatingAdd(result, scrollbarSize.IStartEnd(wm));
   return result;
 }
 
 nscoord nsListControlFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-
   // Always add scrollbar inline sizes to the min-inline-size of the
   // scrolled content. Combobox frames depend on this happening in the
   // dropdown, and standalone listboxes are overflow:scroll so they need
   // it too.
   WritingMode wm = GetWritingMode();
   Maybe<nscoord> containISize = ContainIntrinsicISize();
-  result = containISize ? *containISize
-                        : GetScrolledFrame()->GetMinISize(aRenderingContext);
+  nscoord result = containISize
+                       ? *containISize
+                       : GetScrolledFrame()->GetMinISize(aRenderingContext);
   LogicalMargin scrollbarSize(wm, GetDesiredScrollbarSizes());
   result += scrollbarSize.IStartEnd(wm);
 
diff --git a/layout/forms/nsMeterFrame.cpp b/layout/forms/nsMeterFrame.cpp
index a72a6816d5..31ef52a000 100644
--- a/layout/forms/nsMeterFrame.cpp
+++ b/layout/forms/nsMeterFrame.cpp
@@ -82,7 +82,6 @@ void nsMeterFrame::Reflow(nsPresContext* aPresContext,
                           nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsMeterFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   NS_ASSERTION(mBarDiv, "Meter bar div must exist!");
@@ -93,13 +92,19 @@ void nsMeterFrame::Reflow(nsPresContext* aPresContext,
   nsIFrame* barFrame = mBarDiv->GetPrimaryFrame();
   NS_ASSERTION(barFrame, "The meter frame should have a child with a frame!");
 
-  ReflowBarFrame(barFrame, aPresContext, aReflowInput, aStatus);
-
   const auto wm = aReflowInput.GetWritingMode();
-  aDesiredSize.SetSize(wm, aReflowInput.ComputedSizeWithBorderPadding(wm));
-
+  const auto contentBoxSize = aReflowInput.ComputedSizeWithBSizeFallback([&] {
+    nscoord em = OneEmInAppUnits();
+    return ResolvedOrientationIsVertical() == wm.IsVertical() ? em : 5 * em;
+  });
+  aDesiredSize.SetSize(
+      wm,
+      contentBoxSize + aReflowInput.ComputedLogicalBorderPadding(wm).Size(wm));
   aDesiredSize.SetOverflowAreasToDesiredBounds();
+
+  ReflowBarFrame(barFrame, aPresContext, aReflowInput, contentBoxSize, aStatus);
   ConsiderChildOverflow(aDesiredSize.mOverflowAreas, barFrame);
+
   FinishAndStoreOverflow(&aDesiredSize);
 
   aStatus.Reset();  // This type of frame can't be split.
@@ -108,14 +113,19 @@ void nsMeterFrame::Reflow(nsPresContext* aPresContext,
 void nsMeterFrame::ReflowBarFrame(nsIFrame* aBarFrame,
                                   nsPresContext* aPresContext,
                                   const ReflowInput& aReflowInput,
+                                  const LogicalSize& aParentContentBoxSize,
                                   nsReflowStatus& aStatus) {
   bool vertical = ResolvedOrientationIsVertical();
-  WritingMode wm = aBarFrame->GetWritingMode();
-  LogicalSize availSize = aReflowInput.ComputedSize(wm);
+  const WritingMode wm = aBarFrame->GetWritingMode();
+  const LogicalSize parentSizeInChildWM =
+      aParentContentBoxSize.ConvertTo(wm, aReflowInput.GetWritingMode());
+  const nsSize parentPhysicalSize = parentSizeInChildWM.GetPhysicalSize(wm);
+  LogicalSize availSize = parentSizeInChildWM;
   availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
-  ReflowInput reflowInput(aPresContext, aReflowInput, aBarFrame, availSize);
+  ReflowInput reflowInput(aPresContext, aReflowInput, aBarFrame, availSize,
+                          Some(parentSizeInChildWM));
   nscoord size =
-      vertical ? aReflowInput.ComputedHeight() : aReflowInput.ComputedWidth();
+      vertical ? parentPhysicalSize.Height() : parentPhysicalSize.Width();
   nscoord xoffset = aReflowInput.ComputedPhysicalBorderPadding().left;
   nscoord yoffset = aReflowInput.ComputedPhysicalBorderPadding().top;
 
@@ -123,14 +133,13 @@ void nsMeterFrame::ReflowBarFrame(nsIFrame* aBarFrame,
   size = NSToCoordRound(size * meterElement->Position());
 
   if (!vertical && wm.IsPhysicalRTL()) {
-    xoffset += aReflowInput.ComputedWidth() - size;
+    xoffset += parentPhysicalSize.Width() - size;
   }
 
   // The bar position is *always* constrained.
   if (vertical) {
     // We want the bar to begin at the bottom.
-    yoffset += aReflowInput.ComputedHeight() - size;
-
+    yoffset += parentPhysicalSize.Height() - size;
     size -= reflowInput.ComputedPhysicalMargin().TopBottom() +
             reflowInput.ComputedPhysicalBorderPadding().TopBottom();
     size = std::max(size, 0);
@@ -169,39 +178,12 @@ nsresult nsMeterFrame::AttributeChanged(int32_t aNameSpaceID,
   return nsContainerFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
 }
 
-LogicalSize nsMeterFrame::ComputeAutoSize(
-    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
-    nscoord aAvailableISize, const LogicalSize& aMargin,
-    const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
-    ComputeSizeFlags aFlags) {
-  RefPtr<nsFontMetrics> fontMet =
-      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
-
-  const WritingMode wm = GetWritingMode();
-  LogicalSize autoSize(wm);
-  autoSize.BSize(wm) = autoSize.ISize(wm) =
-      fontMet->Font().size.ToAppUnits();  // 1em
-
-  if (ResolvedOrientationIsVertical() == wm.IsVertical()) {
-    autoSize.ISize(wm) *= 5;  // 5em
-  } else {
-    autoSize.BSize(wm) *= 5;  // 5em
-  }
-
-  return autoSize.ConvertTo(aWM, wm);
-}
-
 nscoord nsMeterFrame::GetMinISize(gfxContext* aRenderingContext) {
-  RefPtr<nsFontMetrics> fontMet =
-      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
-
-  nscoord minISize = fontMet->Font().size.ToAppUnits();  // 1em
-
+  nscoord minISize = OneEmInAppUnits();
   if (ResolvedOrientationIsVertical() == GetWritingMode().IsVertical()) {
     // The orientation is inline
-    minISize *= 5;  // 5em
+    minISize *= 5;
   }
-
   return minISize;
 }
 
diff --git a/layout/forms/nsMeterFrame.h b/layout/forms/nsMeterFrame.h
index 4aa82c1384..7a15878beb 100644
--- a/layout/forms/nsMeterFrame.h
+++ b/layout/forms/nsMeterFrame.h
@@ -7,17 +7,15 @@
 #ifndef nsMeterFrame_h___
 #define nsMeterFrame_h___
 
-#include "mozilla/Attributes.h"
 #include "nsContainerFrame.h"
 #include "nsIAnonymousContentCreator.h"
 #include "nsCOMPtr.h"
-#include "nsCSSPseudoElements.h"
 
 class nsMeterFrame final : public nsContainerFrame,
                            public nsIAnonymousContentCreator
 
 {
-  typedef mozilla::dom::Element Element;
+  using Element = mozilla::dom::Element;
 
  public:
   NS_DECL_QUERYFRAME
@@ -27,36 +25,25 @@ class nsMeterFrame final : public nsContainerFrame,
   virtual ~nsMeterFrame();
 
   void Destroy(DestroyContext&) override;
-
-  virtual void Reflow(nsPresContext* aCX, ReflowOutput& aDesiredSize,
-                      const ReflowInput& aReflowInput,
-                      nsReflowStatus& aStatus) override;
+  void Reflow(nsPresContext*, ReflowOutput&, const ReflowInput&,
+              nsReflowStatus&) override;
 
 #ifdef DEBUG_FRAME_DUMP
-  virtual nsresult GetFrameName(nsAString& aResult) const override {
+  nsresult GetFrameName(nsAString& aResult) const override {
     return MakeFrameName(u"Meter"_ns, aResult);
   }
 #endif
 
   // nsIAnonymousContentCreator
-  virtual nsresult CreateAnonymousContent(
-      nsTArray<ContentInfo>& aElements) override;
-  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
-                                        uint32_t aFilter) override;
+  nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) override;
+  void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
+                                uint32_t aFilter) override;
 
-  virtual nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
-                                    int32_t aModType) override;
+  nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
+                            int32_t aModType) override;
 
-  virtual mozilla::LogicalSize ComputeAutoSize(
-      gfxContext* aRenderingContext, mozilla::WritingMode aWM,
-      const mozilla::LogicalSize& aCBSize, nscoord aAvailableISize,
-      const mozilla::LogicalSize& aMargin,
-      const mozilla::LogicalSize& aBorderPadding,
-      const mozilla::StyleSizeOverrides& aSizeOverrides,
-      mozilla::ComputeSizeFlags aFlags) override;
-
-  virtual nscoord GetMinISize(gfxContext* aRenderingContext) override;
-  virtual nscoord GetPrefISize(gfxContext* aRenderingContext) override;
+  nscoord GetMinISize(gfxContext* aRenderingContext) override;
+  nscoord GetPrefISize(gfxContext* aRenderingContext) override;
 
   /**
    * Returns whether the frame and its child should use the native style.
@@ -66,7 +53,9 @@ class nsMeterFrame final : public nsContainerFrame,
  protected:
   // Helper function which reflow the anonymous div frame.
   void ReflowBarFrame(nsIFrame* aBarFrame, nsPresContext* aPresContext,
-                      const ReflowInput& aReflowInput, nsReflowStatus& aStatus);
+                      const ReflowInput& aReflowInput,
+                      const mozilla::LogicalSize& aParentContentBoxSize,
+                      nsReflowStatus& aStatus);
   /**
    * The div used to show the meter bar.
    * @see nsMeterFrame::CreateAnonymousContent
diff --git a/layout/forms/nsProgressFrame.cpp b/layout/forms/nsProgressFrame.cpp
index 2f0d727473..1cf6bf1447 100644
--- a/layout/forms/nsProgressFrame.cpp
+++ b/layout/forms/nsProgressFrame.cpp
@@ -86,7 +86,6 @@ void nsProgressFrame::Reflow(nsPresContext* aPresContext,
                              nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsProgressFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   NS_ASSERTION(mBarDiv, "Progress bar div must exist!");
@@ -99,11 +98,18 @@ void nsProgressFrame::Reflow(nsPresContext* aPresContext,
                "need to call RegUnregAccessKey only for the first.");
 
   const auto wm = aReflowInput.GetWritingMode();
-  aDesiredSize.SetSize(wm, aReflowInput.ComputedSizeWithBorderPadding(wm));
+  const auto contentBoxSize = aReflowInput.ComputedSizeWithBSizeFallback([&] {
+    nscoord em = OneEmInAppUnits();
+    return ResolvedOrientationIsVertical() == wm.IsVertical() ? em : 10 * em;
+  });
+  aDesiredSize.SetSize(
+      wm,
+      contentBoxSize + aReflowInput.ComputedLogicalBorderPadding(wm).Size(wm));
   aDesiredSize.SetOverflowAreasToDesiredBounds();
 
-  for (auto childFrame : PrincipalChildList()) {
-    ReflowChildFrame(childFrame, aPresContext, aReflowInput, aStatus);
+  for (nsIFrame* childFrame : PrincipalChildList()) {
+    ReflowChildFrame(childFrame, aPresContext, aReflowInput, contentBoxSize,
+                     aStatus);
     ConsiderChildOverflow(aDesiredSize.mOverflowAreas, childFrame);
   }
 
@@ -115,14 +121,19 @@ void nsProgressFrame::Reflow(nsPresContext* aPresContext,
 void nsProgressFrame::ReflowChildFrame(nsIFrame* aChild,
                                        nsPresContext* aPresContext,
                                        const ReflowInput& aReflowInput,
+                                       const LogicalSize& aParentContentBoxSize,
                                        nsReflowStatus& aStatus) {
   bool vertical = ResolvedOrientationIsVertical();
-  WritingMode wm = aChild->GetWritingMode();
-  LogicalSize availSize = aReflowInput.ComputedSize(wm);
+  const WritingMode wm = aChild->GetWritingMode();
+  const LogicalSize parentSizeInChildWM =
+      aParentContentBoxSize.ConvertTo(wm, aReflowInput.GetWritingMode());
+  const nsSize parentPhysicalSize = parentSizeInChildWM.GetPhysicalSize(wm);
+  LogicalSize availSize = parentSizeInChildWM;
   availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
-  ReflowInput reflowInput(aPresContext, aReflowInput, aChild, availSize);
+  ReflowInput reflowInput(aPresContext, aReflowInput, aChild, availSize,
+                          Some(parentSizeInChildWM));
   nscoord size =
-      vertical ? aReflowInput.ComputedHeight() : aReflowInput.ComputedWidth();
+      vertical ? parentPhysicalSize.Height() : parentPhysicalSize.Width();
   nscoord xoffset = aReflowInput.ComputedPhysicalBorderPadding().left;
   nscoord yoffset = aReflowInput.ComputedPhysicalBorderPadding().top;
 
@@ -135,7 +146,7 @@ void nsProgressFrame::ReflowChildFrame(nsIFrame* aChild,
   }
 
   if (!vertical && wm.IsPhysicalRTL()) {
-    xoffset += aReflowInput.ComputedWidth() - size;
+    xoffset += parentPhysicalSize.Width() - size;
   }
 
   // The bar size is fixed in these cases:
@@ -148,8 +159,7 @@ void nsProgressFrame::ReflowChildFrame(nsIFrame* aChild,
   if (position != -1 || ShouldUseNativeStyle()) {
     if (vertical) {
       // We want the bar to begin at the bottom.
-      yoffset += aReflowInput.ComputedHeight() - size;
-
+      yoffset += parentPhysicalSize.Height() - size;
       size -= reflowInput.ComputedPhysicalMargin().TopBottom() +
               reflowInput.ComputedPhysicalBorderPadding().TopBottom();
       size = std::max(size, 0);
@@ -161,10 +171,12 @@ void nsProgressFrame::ReflowChildFrame(nsIFrame* aChild,
       reflowInput.SetComputedWidth(size);
     }
   } else if (vertical) {
-    // For vertical progress bars, we need to position the bar specificly when
+    // For vertical progress bars, we need to position the bar specifically when
     // the width isn't constrained (position == -1 and !ShouldUseNativeStyle())
-    // because aReflowInput.ComputedHeight() - size == 0.
-    yoffset += aReflowInput.ComputedHeight() - reflowInput.ComputedHeight();
+    // because parentPhysiscalSize.Height() - size == 0.
+    // FIXME(emilio): This assumes that the bar's height is constrained, which
+    // seems like a wrong assumption?
+    yoffset += parentPhysicalSize.Height() - reflowInput.ComputedHeight();
   }
 
   xoffset += reflowInput.ComputedPhysicalMargin().left;
@@ -195,38 +207,11 @@ nsresult nsProgressFrame::AttributeChanged(int32_t aNameSpaceID,
   return nsContainerFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
 }
 
-LogicalSize nsProgressFrame::ComputeAutoSize(
-    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
-    nscoord aAvailableISize, const LogicalSize& aMargin,
-    const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
-    ComputeSizeFlags aFlags) {
-  const WritingMode wm = GetWritingMode();
-  LogicalSize autoSize(wm);
-  autoSize.BSize(wm) = autoSize.ISize(wm) =
-      StyleFont()
-          ->mFont.size.ScaledBy(nsLayoutUtils::FontSizeInflationFor(this))
-          .ToAppUnits();  // 1em
-
-  if (ResolvedOrientationIsVertical() == wm.IsVertical()) {
-    autoSize.ISize(wm) *= 10;  // 10em
-  } else {
-    autoSize.BSize(wm) *= 10;  // 10em
-  }
-
-  return autoSize.ConvertTo(aWM, wm);
-}
-
 nscoord nsProgressFrame::GetMinISize(gfxContext* aRenderingContext) {
-  RefPtr<nsFontMetrics> fontMet =
-      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
-
-  nscoord minISize = fontMet->Font().size.ToAppUnits();  // 1em
-
+  nscoord minISize = OneEmInAppUnits();
   if (ResolvedOrientationIsVertical() == GetWritingMode().IsVertical()) {
-    // The orientation is inline
-    minISize *= 10;  // 10em
+    minISize *= 10;
   }
-
   return minISize;
 }
 
diff --git a/layout/forms/nsProgressFrame.h b/layout/forms/nsProgressFrame.h
index 7d3618ee96..f8917ba4f2 100644
--- a/layout/forms/nsProgressFrame.h
+++ b/layout/forms/nsProgressFrame.h
@@ -18,8 +18,7 @@ enum class PseudoStyleType : uint8_t;
 
 class nsProgressFrame final : public nsContainerFrame,
                               public nsIAnonymousContentCreator {
-  typedef mozilla::PseudoStyleType PseudoStyleType;
-  typedef mozilla::dom::Element Element;
+  using Element = mozilla::dom::Element;
 
  public:
   NS_DECL_QUERYFRAME
@@ -30,38 +29,28 @@ class nsProgressFrame final : public nsContainerFrame,
 
   void Destroy(DestroyContext&) override;
 
-  virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
-                                const nsDisplayListSet& aLists) override;
+  void BuildDisplayList(nsDisplayListBuilder* aBuilder,
+                        const nsDisplayListSet& aLists) override;
 
-  virtual void Reflow(nsPresContext* aCX, ReflowOutput& aDesiredSize,
-                      const ReflowInput& aReflowInput,
-                      nsReflowStatus& aStatus) override;
+  void Reflow(nsPresContext*, ReflowOutput&, const ReflowInput&,
+              nsReflowStatus&) override;
 
 #ifdef DEBUG_FRAME_DUMP
-  virtual nsresult GetFrameName(nsAString& aResult) const override {
+  nsresult GetFrameName(nsAString& aResult) const override {
     return MakeFrameName(u"Progress"_ns, aResult);
   }
 #endif
 
   // nsIAnonymousContentCreator
-  virtual nsresult CreateAnonymousContent(
-      nsTArray<ContentInfo>& aElements) override;
-  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
-                                        uint32_t aFilter) override;
+  nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) override;
+  void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
+                                uint32_t aFilter) override;
 
-  virtual nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
-                                    int32_t aModType) override;
+  nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
+                            int32_t aModType) override;
 
-  virtual mozilla::LogicalSize ComputeAutoSize(
-      gfxContext* aRenderingContext, mozilla::WritingMode aWM,
-      const mozilla::LogicalSize& aCBSize, nscoord aAvailableISize,
-      const mozilla::LogicalSize& aMargin,
-      const mozilla::LogicalSize& aBorderPadding,
-      const mozilla::StyleSizeOverrides& aSizeOverrides,
-      mozilla::ComputeSizeFlags aFlags) override;
-
-  virtual nscoord GetMinISize(gfxContext* aRenderingContext) override;
-  virtual nscoord GetPrefISize(gfxContext* aRenderingContext) override;
+  nscoord GetMinISize(gfxContext* aRenderingContext) override;
+  nscoord GetPrefISize(gfxContext* aRenderingContext) override;
 
   /**
    * Returns whether the frame and its child should use the native style.
@@ -72,6 +61,7 @@ class nsProgressFrame final : public nsContainerFrame,
   // Helper function to reflow a child frame.
   void ReflowChildFrame(nsIFrame* aChild, nsPresContext* aPresContext,
                         const ReflowInput& aReflowInput,
+                        const mozilla::LogicalSize& aParentContentBoxSize,
                         nsReflowStatus& aStatus);
 
   /**
diff --git a/layout/forms/nsRangeFrame.cpp b/layout/forms/nsRangeFrame.cpp
index 2cccff715a..3238d0372f 100644
--- a/layout/forms/nsRangeFrame.cpp
+++ b/layout/forms/nsRangeFrame.cpp
@@ -155,7 +155,6 @@ void nsRangeFrame::Reflow(nsPresContext* aPresContext,
                           nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsRangeFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   NS_ASSERTION(mTrackDiv, "::-moz-range-track div must exist!");
@@ -166,35 +165,17 @@ void nsRangeFrame::Reflow(nsPresContext* aPresContext,
                "need to call RegUnregAccessKey only for the first.");
 
   WritingMode wm = aReflowInput.GetWritingMode();
-  nscoord computedBSize = aReflowInput.ComputedBSize();
-  if (computedBSize == NS_UNCONSTRAINEDSIZE) {
-    computedBSize = 0;
-  }
-  const auto borderPadding = aReflowInput.ComputedLogicalBorderPadding(wm);
-  LogicalSize finalSize(
-      wm, aReflowInput.ComputedISize() + borderPadding.IStartEnd(wm),
-      computedBSize + borderPadding.BStartEnd(wm));
-  aDesiredSize.SetSize(wm, finalSize);
-
-  ReflowAnonymousContent(aPresContext, aDesiredSize, aReflowInput);
-
+  const auto contentBoxSize = aReflowInput.ComputedSizeWithBSizeFallback([&] {
+    return IsInlineOriented() ? AutoCrossSize()
+                              : OneEmInAppUnits() * MAIN_AXIS_EM_SIZE;
+  });
+  aDesiredSize.SetSize(
+      wm,
+      contentBoxSize + aReflowInput.ComputedLogicalBorderPadding(wm).Size(wm));
   aDesiredSize.SetOverflowAreasToDesiredBounds();
 
-  nsIFrame* trackFrame = mTrackDiv->GetPrimaryFrame();
-  if (trackFrame) {
-    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, trackFrame);
-  }
-
-  nsIFrame* rangeProgressFrame = mProgressDiv->GetPrimaryFrame();
-  if (rangeProgressFrame) {
-    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, rangeProgressFrame);
-  }
-
-  nsIFrame* thumbFrame = mThumbDiv->GetPrimaryFrame();
-  if (thumbFrame) {
-    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, thumbFrame);
-  }
-
+  ReflowAnonymousContent(aPresContext, aDesiredSize, contentBoxSize,
+                         aReflowInput);
   FinishAndStoreOverflow(&aDesiredSize);
 
   MOZ_ASSERT(aStatus.IsEmpty(), "This type of frame can't be split.");
@@ -202,111 +183,71 @@ void nsRangeFrame::Reflow(nsPresContext* aPresContext,
 
 void nsRangeFrame::ReflowAnonymousContent(nsPresContext* aPresContext,
                                           ReflowOutput& aDesiredSize,
+                                          const LogicalSize& aContentBoxSize,
                                           const ReflowInput& aReflowInput) {
+  const auto parentWM = aReflowInput.GetWritingMode();
   // The width/height of our content box, which is the available width/height
-  // for our anonymous content:
-  nscoord rangeFrameContentBoxWidth = aReflowInput.ComputedWidth();
-  nscoord rangeFrameContentBoxHeight = aReflowInput.ComputedHeight();
-  if (rangeFrameContentBoxHeight == NS_UNCONSTRAINEDSIZE) {
-    rangeFrameContentBoxHeight = 0;
-  }
-
-  nsIFrame* trackFrame = mTrackDiv->GetPrimaryFrame();
-
-  if (trackFrame) {  // display:none?
-
-    // Position the track:
-    // The idea here is that we allow content authors to style the width,
-    // height, border and padding of the track, but we ignore margin and
-    // positioning properties and do the positioning ourself to keep the center
-    // of the track's border box on the center of the nsRangeFrame's content
-    // box.
-
-    WritingMode wm = trackFrame->GetWritingMode();
-    LogicalSize availSize = aReflowInput.ComputedSize(wm);
-    availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
-    ReflowInput trackReflowInput(aPresContext, aReflowInput, trackFrame,
-                                 availSize);
-
-    // Find the x/y position of the track frame such that it will be positioned
-    // as described above. These coordinates are with respect to the
-    // nsRangeFrame's border-box.
-    nscoord trackX = rangeFrameContentBoxWidth / 2;
-    nscoord trackY = rangeFrameContentBoxHeight / 2;
-
-    // Account for the track's border and padding (we ignore its margin):
-    trackX -= trackReflowInput.ComputedPhysicalBorderPadding().left +
-              trackReflowInput.ComputedWidth() / 2;
-    trackY -= trackReflowInput.ComputedPhysicalBorderPadding().top +
-              trackReflowInput.ComputedHeight() / 2;
-
-    // Make relative to our border box instead of our content box:
-    trackX += aReflowInput.ComputedPhysicalBorderPadding().left;
-    trackY += aReflowInput.ComputedPhysicalBorderPadding().top;
-
-    nsReflowStatus frameStatus;
-    ReflowOutput trackDesiredSize(aReflowInput);
-    ReflowChild(trackFrame, aPresContext, trackDesiredSize, trackReflowInput,
-                trackX, trackY, ReflowChildFlags::Default, frameStatus);
-    MOZ_ASSERT(
-        frameStatus.IsFullyComplete(),
-        "We gave our child unconstrained height, so it should be complete");
-    FinishReflowChild(trackFrame, aPresContext, trackDesiredSize,
-                      &trackReflowInput, trackX, trackY,
-                      ReflowChildFlags::Default);
-  }
-
-  nsIFrame* thumbFrame = mThumbDiv->GetPrimaryFrame();
-
-  if (thumbFrame) {  // display:none?
-    WritingMode wm = thumbFrame->GetWritingMode();
-    LogicalSize availSize = aReflowInput.ComputedSize(wm);
-    availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
-    ReflowInput thumbReflowInput(aPresContext, aReflowInput, thumbFrame,
-                                 availSize);
-
-    // Where we position the thumb depends on its size, so we first reflow
-    // the thumb at {0,0} to obtain its size, then position it afterwards.
-
-    nsReflowStatus frameStatus;
-    ReflowOutput thumbDesiredSize(aReflowInput);
-    ReflowChild(thumbFrame, aPresContext, thumbDesiredSize, thumbReflowInput, 0,
-                0, ReflowChildFlags::Default, frameStatus);
-    MOZ_ASSERT(
-        frameStatus.IsFullyComplete(),
-        "We gave our child unconstrained height, so it should be complete");
-    FinishReflowChild(thumbFrame, aPresContext, thumbDesiredSize,
-                      &thumbReflowInput, 0, 0, ReflowChildFlags::Default);
-    DoUpdateThumbPosition(thumbFrame,
-                          nsSize(aDesiredSize.Width(), aDesiredSize.Height()));
-  }
-
-  nsIFrame* rangeProgressFrame = mProgressDiv->GetPrimaryFrame();
-
-  if (rangeProgressFrame) {  // display:none?
-    WritingMode wm = rangeProgressFrame->GetWritingMode();
-    LogicalSize availSize = aReflowInput.ComputedSize(wm);
+  // for our anonymous content.
+  const nsSize rangeFrameContentBoxSize =
+      aContentBoxSize.GetPhysicalSize(parentWM);
+  for (auto* div : {mTrackDiv.get(), mThumbDiv.get(), mProgressDiv.get()}) {
+    nsIFrame* child = div->GetPrimaryFrame();
+    if (!child) {
+      continue;
+    }
+    const WritingMode wm = child->GetWritingMode();
+    const LogicalSize parentSizeInChildWM =
+        aContentBoxSize.ConvertTo(wm, parentWM);
+    LogicalSize availSize = parentSizeInChildWM;
     availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
-    ReflowInput progressReflowInput(aPresContext, aReflowInput,
-                                    rangeProgressFrame, availSize);
-
-    // We first reflow the range-progress frame at {0,0} to obtain its
-    // unadjusted dimensions, then we adjust it to so that the appropriate edge
-    // ends at the thumb.
+    ReflowInput childReflowInput(aPresContext, aReflowInput, child, availSize,
+                                 Some(parentSizeInChildWM));
+
+    const nsPoint pos = [&] {
+      if (div != mTrackDiv) {
+        // Where we position the thumb and range-progress depends on its size,
+        // so we first reflow them at {0,0} to obtain the size, then position
+        // them afterwards.
+        return nsPoint();
+      }
+      // Find the x/y position of the track. The idea here is that we allow
+      // content authors to style the width, height, border and padding of the
+      // track, but we ignore margin and positioning properties and do the
+      // positioning ourself to keep the center of the track's border box on the
+      // center of the nsRangeFrame's content. These coordinates are with
+      // respect to the nsRangeFrame's border-box.
+      nscoord trackX = rangeFrameContentBoxSize.Width() / 2;
+      nscoord trackY = rangeFrameContentBoxSize.Height() / 2;
+
+      // Account for the track's border and padding (we ignore its margin):
+      // FIXME(emilio): Assumes the track height is constrained, which might not
+      // be true if authors override it.
+      trackX -= childReflowInput.ComputedPhysicalBorderPadding().left +
+                childReflowInput.ComputedWidth() / 2;
+      trackY -= childReflowInput.ComputedPhysicalBorderPadding().top +
+                childReflowInput.ComputedHeight() / 2;
+
+      // Make relative to our border box instead of our content box:
+      trackX += aReflowInput.ComputedPhysicalBorderPadding().left;
+      trackY += aReflowInput.ComputedPhysicalBorderPadding().top;
+      return nsPoint(trackX, trackY);
+    }();
 
     nsReflowStatus frameStatus;
-    ReflowOutput progressDesiredSize(aReflowInput);
-    ReflowChild(rangeProgressFrame, aPresContext, progressDesiredSize,
-                progressReflowInput, 0, 0, ReflowChildFlags::Default,
-                frameStatus);
+    ReflowOutput childDesiredSize(aReflowInput);
+    ReflowChild(child, aPresContext, childDesiredSize, childReflowInput, pos.x,
+                pos.y, ReflowChildFlags::Default, frameStatus);
     MOZ_ASSERT(
         frameStatus.IsFullyComplete(),
         "We gave our child unconstrained height, so it should be complete");
-    FinishReflowChild(rangeProgressFrame, aPresContext, progressDesiredSize,
-                      &progressReflowInput, 0, 0, ReflowChildFlags::Default);
-    DoUpdateRangeProgressFrame(
-        rangeProgressFrame,
-        nsSize(aDesiredSize.Width(), aDesiredSize.Height()));
+    FinishReflowChild(child, aPresContext, childDesiredSize, &childReflowInput,
+                      pos.x, pos.y, ReflowChildFlags::Default);
+    if (div == mThumbDiv) {
+      DoUpdateThumbPosition(child, rangeFrameContentBoxSize);
+    } else if (div == mProgressDiv) {
+      DoUpdateRangeProgressFrame(child, rangeFrameContentBoxSize);
+    }
+    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, child);
   }
 }
 
@@ -388,7 +329,7 @@ Decimal nsRangeFrame::GetValueAtEventPoint(WidgetGUIEvent* aEvent) {
         ->GetValueAsDecimal();
   }
 
-  nsRect rangeContentRect = GetContentRectRelativeToSelf();
+  const nsRect rangeContentRect = GetContentRectRelativeToSelf();
   nsSize thumbSize;
 
   if (IsThemed()) {
@@ -455,11 +396,12 @@ void nsRangeFrame::UpdateForValueChange() {
   if (!rangeProgressFrame && !thumbFrame) {
     return;  // diplay:none?
   }
+  const nsSize contentBoxSize = GetContentRect().Size();
   if (rangeProgressFrame) {
-    DoUpdateRangeProgressFrame(rangeProgressFrame, GetSize());
+    DoUpdateRangeProgressFrame(rangeProgressFrame, contentBoxSize);
   }
   if (thumbFrame) {
-    DoUpdateThumbPosition(thumbFrame, GetSize());
+    DoUpdateThumbPosition(thumbFrame, contentBoxSize);
   }
   if (IsThemed()) {
     // We don't know the exact dimensions or location of the thumb when native
@@ -539,7 +481,7 @@ mozilla::dom::HTMLInputElement& nsRangeFrame::InputElement() const {
 }
 
 void nsRangeFrame::DoUpdateThumbPosition(nsIFrame* aThumbFrame,
-                                         const nsSize& aRangeSize) {
+                                         const nsSize& aRangeContentBoxSize) {
   MOZ_ASSERT(aThumbFrame);
 
   // The idea here is that we want to position the thumb so that the center
@@ -553,29 +495,26 @@ void nsRangeFrame::DoUpdateThumbPosition(nsIFrame* aThumbFrame,
   nsMargin borderAndPadding = GetUsedBorderAndPadding();
   nsPoint newPosition(borderAndPadding.left, borderAndPadding.top);
 
-  nsSize rangeContentBoxSize(aRangeSize);
-  rangeContentBoxSize.width -= borderAndPadding.LeftRight();
-  rangeContentBoxSize.height -= borderAndPadding.TopBottom();
-
   nsSize thumbSize = aThumbFrame->GetSize();
   double fraction = GetValueAsFractionOfRange();
   MOZ_ASSERT(fraction >= 0.0 && fraction <= 1.0);
 
   if (IsHorizontal()) {
-    if (thumbSize.width < rangeContentBoxSize.width) {
-      nscoord traversableDistance = rangeContentBoxSize.width - thumbSize.width;
+    if (thumbSize.width < aRangeContentBoxSize.width) {
+      nscoord traversableDistance =
+          aRangeContentBoxSize.width - thumbSize.width;
       if (IsRightToLeft()) {
         newPosition.x += NSToCoordRound((1.0 - fraction) * traversableDistance);
       } else {
         newPosition.x += NSToCoordRound(fraction * traversableDistance);
       }
-      newPosition.y += (rangeContentBoxSize.height - thumbSize.height) / 2;
+      newPosition.y += (aRangeContentBoxSize.height - thumbSize.height) / 2;
     }
   } else {
-    if (thumbSize.height < rangeContentBoxSize.height) {
+    if (thumbSize.height < aRangeContentBoxSize.height) {
       nscoord traversableDistance =
-          rangeContentBoxSize.height - thumbSize.height;
-      newPosition.x += (rangeContentBoxSize.width - thumbSize.width) / 2;
+          aRangeContentBoxSize.height - thumbSize.height;
+      newPosition.x += (aRangeContentBoxSize.width - thumbSize.width) / 2;
       if (IsUpwards()) {
         newPosition.y += NSToCoordRound((1.0 - fraction) * traversableDistance);
       } else {
@@ -586,9 +525,9 @@ void nsRangeFrame::DoUpdateThumbPosition(nsIFrame* aThumbFrame,
   aThumbFrame->SetPosition(newPosition);
 }
 
-void nsRangeFrame::DoUpdateRangeProgressFrame(nsIFrame* aRangeProgressFrame,
-                                              const nsSize& aRangeSize) {
-  MOZ_ASSERT(aRangeProgressFrame);
+void nsRangeFrame::DoUpdateRangeProgressFrame(
+    nsIFrame* aProgressFrame, const nsSize& aRangeContentBoxSize) {
+  MOZ_ASSERT(aProgressFrame);
 
   // The idea here is that we want to position the ::-moz-range-progress
   // pseudo-element so that the center line running along its length is on the
@@ -598,35 +537,30 @@ void nsRangeFrame::DoUpdateRangeProgressFrame(nsIFrame* aRangeProgressFrame,
   // nsRangeFrame's content box, and we size the progress element's border-box
   // to have a length of GetValueAsFractionOfRange() times the nsRangeFrame's
   // content-box size.
-
   nsMargin borderAndPadding = GetUsedBorderAndPadding();
-  nsSize progSize = aRangeProgressFrame->GetSize();
+  nsSize progSize = aProgressFrame->GetSize();
   nsRect progRect(borderAndPadding.left, borderAndPadding.top, progSize.width,
                   progSize.height);
 
-  nsSize rangeContentBoxSize(aRangeSize);
-  rangeContentBoxSize.width -= borderAndPadding.LeftRight();
-  rangeContentBoxSize.height -= borderAndPadding.TopBottom();
-
   double fraction = GetValueAsFractionOfRange();
   MOZ_ASSERT(fraction >= 0.0 && fraction <= 1.0);
 
   if (IsHorizontal()) {
-    nscoord progLength = NSToCoordRound(fraction * rangeContentBoxSize.width);
+    nscoord progLength = NSToCoordRound(fraction * aRangeContentBoxSize.width);
     if (IsRightToLeft()) {
-      progRect.x += rangeContentBoxSize.width - progLength;
+      progRect.x += aRangeContentBoxSize.width - progLength;
     }
-    progRect.y += (rangeContentBoxSize.height - progSize.height) / 2;
+    progRect.y += (aRangeContentBoxSize.height - progSize.height) / 2;
     progRect.width = progLength;
   } else {
-    nscoord progLength = NSToCoordRound(fraction * rangeContentBoxSize.height);
-    progRect.x += (rangeContentBoxSize.width - progSize.width) / 2;
+    nscoord progLength = NSToCoordRound(fraction * aRangeContentBoxSize.height);
+    progRect.x += (aRangeContentBoxSize.width - progSize.width) / 2;
     if (IsUpwards()) {
-      progRect.y += rangeContentBoxSize.height - progLength;
+      progRect.y += aRangeContentBoxSize.height - progLength;
     }
     progRect.height = progLength;
   }
-  aRangeProgressFrame->SetRect(progRect);
+  aProgressFrame->SetRect(progRect);
 }
 
 nsresult nsRangeFrame::AttributeChanged(int32_t aNameSpaceID,
@@ -677,7 +611,7 @@ nsresult nsRangeFrame::AttributeChanged(int32_t aNameSpaceID,
   return nsContainerFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
 }
 
-nscoord nsRangeFrame::AutoCrossSize(Length aEm) {
+nscoord nsRangeFrame::AutoCrossSize() {
   nscoord minCrossSize(0);
   if (IsThemed()) {
     nsPresContext* pc = PresContext();
@@ -686,33 +620,8 @@ nscoord nsRangeFrame::AutoCrossSize(Length aEm) {
     minCrossSize =
         pc->DevPixelsToAppUnits(IsHorizontal() ? size.height : size.width);
   }
-  return std::max(minCrossSize, aEm.ScaledBy(CROSS_AXIS_EM_SIZE).ToAppUnits());
-}
-
-static mozilla::Length OneEm(nsRangeFrame* aFrame) {
-  return aFrame->StyleFont()->mFont.size.ScaledBy(
-      nsLayoutUtils::FontSizeInflationFor(aFrame));
-}
-
-LogicalSize nsRangeFrame::ComputeAutoSize(
-    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
-    nscoord aAvailableISize, const LogicalSize& aMargin,
-    const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
-    ComputeSizeFlags aFlags) {
-  bool isInlineOriented = IsInlineOriented();
-  auto em = OneEm(this);
-
-  const WritingMode wm = GetWritingMode();
-  LogicalSize autoSize(wm);
-  if (isInlineOriented) {
-    autoSize.ISize(wm) = em.ScaledBy(MAIN_AXIS_EM_SIZE).ToAppUnits();
-    autoSize.BSize(wm) = AutoCrossSize(em);
-  } else {
-    autoSize.ISize(wm) = AutoCrossSize(em);
-    autoSize.BSize(wm) = em.ScaledBy(MAIN_AXIS_EM_SIZE).ToAppUnits();
-  }
-
-  return autoSize.ConvertTo(aWM, wm);
+  return std::max(minCrossSize,
+                  NSToCoordRound(OneEmInAppUnits() * CROSS_AXIS_EM_SIZE));
 }
 
 nscoord nsRangeFrame::GetMinISize(gfxContext* aRenderingContext) {
@@ -728,11 +637,10 @@ nscoord nsRangeFrame::GetMinISize(gfxContext* aRenderingContext) {
 }
 
 nscoord nsRangeFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  auto em = OneEm(this);
   if (IsInlineOriented()) {
-    return em.ScaledBy(MAIN_AXIS_EM_SIZE).ToAppUnits();
+    return OneEmInAppUnits() * MAIN_AXIS_EM_SIZE;
   }
-  return AutoCrossSize(em);
+  return AutoCrossSize();
 }
 
 bool nsRangeFrame::IsHorizontal() const {
diff --git a/layout/forms/nsRangeFrame.h b/layout/forms/nsRangeFrame.h
index 4d2073aa50..10d0fc0095 100644
--- a/layout/forms/nsRangeFrame.h
+++ b/layout/forms/nsRangeFrame.h
@@ -7,12 +7,10 @@
 #ifndef nsRangeFrame_h___
 #define nsRangeFrame_h___
 
-#include "mozilla/Attributes.h"
 #include "mozilla/Decimal.h"
 #include "mozilla/EventForwards.h"
 #include "nsContainerFrame.h"
 #include "nsIAnonymousContentCreator.h"
-#include "nsIDOMEventListener.h"
 #include "nsCOMPtr.h"
 #include "nsTArray.h"
 
@@ -40,8 +38,7 @@ class nsRangeFrame final : public nsContainerFrame,
   explicit nsRangeFrame(ComputedStyle* aStyle, nsPresContext* aPresContext);
   virtual ~nsRangeFrame();
 
-  typedef mozilla::PseudoStyleType PseudoStyleType;
-  typedef mozilla::dom::Element Element;
+  using Element = mozilla::dom::Element;
 
  public:
   NS_DECL_QUERYFRAME
@@ -53,39 +50,30 @@ class nsRangeFrame final : public nsContainerFrame,
   void BuildDisplayList(nsDisplayListBuilder* aBuilder,
                         const nsDisplayListSet& aLists) override;
 
-  virtual void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
-                      const ReflowInput& aReflowInput,
-                      nsReflowStatus& aStatus) override;
+  void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
+              const ReflowInput& aReflowInput,
+              nsReflowStatus& aStatus) override;
 
 #ifdef DEBUG_FRAME_DUMP
-  virtual nsresult GetFrameName(nsAString& aResult) const override {
+  nsresult GetFrameName(nsAString& aResult) const override {
     return MakeFrameName(u"Range"_ns, aResult);
   }
 #endif
 
 #ifdef ACCESSIBILITY
-  virtual mozilla::a11y::AccType AccessibleType() override;
+  mozilla::a11y::AccType AccessibleType() override;
 #endif
 
   // nsIAnonymousContentCreator
-  virtual nsresult CreateAnonymousContent(
-      nsTArray<ContentInfo>& aElements) override;
-  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
-                                        uint32_t aFilter) override;
+  nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) override;
+  void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
+                                uint32_t aFilter) override;
 
-  virtual nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
-                                    int32_t aModType) override;
+  nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
+                            int32_t aModType) override;
 
-  mozilla::LogicalSize ComputeAutoSize(
-      gfxContext* aRenderingContext, mozilla::WritingMode aWM,
-      const mozilla::LogicalSize& aCBSize, nscoord aAvailableISize,
-      const mozilla::LogicalSize& aMargin,
-      const mozilla::LogicalSize& aBorderPadding,
-      const mozilla::StyleSizeOverrides& aSizeOverrides,
-      mozilla::ComputeSizeFlags aFlags) override;
-
-  virtual nscoord GetMinISize(gfxContext* aRenderingContext) override;
-  virtual nscoord GetPrefISize(gfxContext* aRenderingContext) override;
+  nscoord GetMinISize(gfxContext* aRenderingContext) override;
+  nscoord GetPrefISize(gfxContext* aRenderingContext) override;
 
   /**
    * Returns true if the slider's thumb moves horizontally, or else false if it
@@ -171,17 +159,19 @@ class nsRangeFrame final : public nsContainerFrame,
  private:
   // Return our preferred size in the cross-axis (the axis perpendicular
   // to the direction of movement of the thumb).
-  nscoord AutoCrossSize(mozilla::Length aEm);
+  nscoord AutoCrossSize();
 
   // Helper function which reflows the anonymous div frames.
   void ReflowAnonymousContent(nsPresContext* aPresContext,
                               ReflowOutput& aDesiredSize,
+                              const mozilla::LogicalSize& aContentBoxSize,
                               const ReflowInput& aReflowInput);
 
-  void DoUpdateThumbPosition(nsIFrame* aThumbFrame, const nsSize& aRangeSize);
+  void DoUpdateThumbPosition(nsIFrame* aThumbFrame,
+                             const nsSize& aRangeContentBoxSize);
 
   void DoUpdateRangeProgressFrame(nsIFrame* aProgressFrame,
-                                  const nsSize& aRangeSize);
+                                  const nsSize& aRangeContentBoxSize);
 
   /**
    * The div used to show the ::-moz-range-track pseudo-element.
diff --git a/layout/forms/nsTextControlFrame.cpp b/layout/forms/nsTextControlFrame.cpp
index c51b94c56a..32e817be8a 100644
--- a/layout/forms/nsTextControlFrame.cpp
+++ b/layout/forms/nsTextControlFrame.cpp
@@ -173,15 +173,14 @@ void nsTextControlFrame::Destroy(DestroyContext& aContext) {
   nsContainerFrame::Destroy(aContext);
 }
 
-LogicalSize nsTextControlFrame::CalcIntrinsicSize(
-    gfxContext* aRenderingContext, WritingMode aWM,
-    float aFontSizeInflation) const {
+LogicalSize nsTextControlFrame::CalcIntrinsicSize(gfxContext* aRenderingContext,
+                                                  WritingMode aWM) const {
   LogicalSize intrinsicSize(aWM);
+  const float inflation = nsLayoutUtils::FontSizeInflationFor(this);
   RefPtr<nsFontMetrics> fontMet =
-      nsLayoutUtils::GetFontMetricsForFrame(this, aFontSizeInflation);
-  const nscoord lineHeight =
-      ReflowInput::CalcLineHeight(*Style(), PresContext(), GetContent(),
-                                  NS_UNCONSTRAINEDSIZE, aFontSizeInflation);
+      nsLayoutUtils::GetFontMetricsForFrame(this, inflation);
+  const nscoord lineHeight = ReflowInput::CalcLineHeight(
+      *Style(), PresContext(), GetContent(), NS_UNCONSTRAINEDSIZE, inflation);
   // Use the larger of the font's "average" char width or the width of the
   // zero glyph (if present) as the basis for resolving the size attribute.
   const nscoord charWidth =
@@ -554,58 +553,14 @@ void nsTextControlFrame::AppendAnonymousContentTo(
 }
 
 nscoord nsTextControlFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  float inflation = nsLayoutUtils::FontSizeInflationFor(this);
   WritingMode wm = GetWritingMode();
-  result = CalcIntrinsicSize(aRenderingContext, wm, inflation).ISize(wm);
-  return result;
+  return CalcIntrinsicSize(aRenderingContext, wm).ISize(wm);
 }
 
 nscoord nsTextControlFrame::GetMinISize(gfxContext* aRenderingContext) {
-  // Our min inline size is just our preferred width if we have auto inline size
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  result = GetPrefISize(aRenderingContext);
-  return result;
-}
-
-LogicalSize nsTextControlFrame::ComputeAutoSize(
-    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
-    nscoord aAvailableISize, const LogicalSize& aMargin,
-    const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
-    ComputeSizeFlags aFlags) {
-  float inflation = nsLayoutUtils::FontSizeInflationFor(this);
-  LogicalSize autoSize = CalcIntrinsicSize(aRenderingContext, aWM, inflation);
-
-  // Note: nsContainerFrame::ComputeAutoSize only computes the inline-size (and
-  // only for 'auto'), the block-size it returns is always NS_UNCONSTRAINEDSIZE.
-  const auto& styleISize = aSizeOverrides.mStyleISize
-                               ? *aSizeOverrides.mStyleISize
-                               : StylePosition()->ISize(aWM);
-  if (styleISize.IsAuto()) {
-    if (aFlags.contains(ComputeSizeFlag::IClampMarginBoxMinSize)) {
-      // CalcIntrinsicSize isn't aware of grid-item margin-box clamping, so we
-      // fall back to nsContainerFrame's ComputeAutoSize to handle that.
-      // XXX maybe a font-inflation issue here? (per the assertion below).
-      autoSize.ISize(aWM) =
-          nsContainerFrame::ComputeAutoSize(
-              aRenderingContext, aWM, aCBSize, aAvailableISize, aMargin,
-              aBorderPadding, aSizeOverrides, aFlags)
-              .ISize(aWM);
-    }
-#ifdef DEBUG
-    else {
-      LogicalSize ancestorAutoSize = nsContainerFrame::ComputeAutoSize(
-          aRenderingContext, aWM, aCBSize, aAvailableISize, aMargin,
-          aBorderPadding, aSizeOverrides, aFlags);
-      MOZ_ASSERT(inflation != 1.0f ||
-                     ancestorAutoSize.ISize(aWM) == autoSize.ISize(aWM),
-                 "Incorrect size computed by ComputeAutoSize?");
-    }
-#endif
-  }
-  return autoSize;
+  // Our min inline size is just our preferred inline-size if we have auto
+  // inline size.
+  return GetPrefISize(aRenderingContext);
 }
 
 Maybe<nscoord> nsTextControlFrame::ComputeBaseline(
@@ -641,12 +596,16 @@ void nsTextControlFrame::Reflow(nsPresContext* aPresContext,
                                 nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTextControlFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // set values of reflow's out parameters
   WritingMode wm = aReflowInput.GetWritingMode();
-  aDesiredSize.SetSize(wm, aReflowInput.ComputedSizeWithBorderPadding(wm));
+  const auto contentBoxSize = aReflowInput.ComputedSizeWithBSizeFallback([&] {
+    return CalcIntrinsicSize(aReflowInput.mRenderingContext, wm).BSize(wm);
+  });
+  aDesiredSize.SetSize(
+      wm,
+      contentBoxSize + aReflowInput.ComputedLogicalBorderPadding(wm).Size(wm));
 
   {
     // Calculate the baseline and store it in mFirstBaseline.
@@ -674,7 +633,7 @@ void nsTextControlFrame::Reflow(nsPresContext* aPresContext,
   nscoord buttonBoxISize = 0;
   if (buttonBox) {
     ReflowTextControlChild(buttonBox, aPresContext, aReflowInput, aStatus,
-                           aDesiredSize, buttonBoxISize);
+                           aDesiredSize, contentBoxSize, buttonBoxISize);
   }
 
   // perform reflow on all kids
@@ -684,7 +643,7 @@ void nsTextControlFrame::Reflow(nsPresContext* aPresContext,
       MOZ_ASSERT(!IsButtonBox(kid),
                  "Should only have one button box, and should be last");
       ReflowTextControlChild(kid, aPresContext, aReflowInput, aStatus,
-                             aDesiredSize, buttonBoxISize);
+                             aDesiredSize, contentBoxSize, buttonBoxISize);
     }
     kid = kid->GetNextSibling();
   }
@@ -698,22 +657,28 @@ void nsTextControlFrame::Reflow(nsPresContext* aPresContext,
 void nsTextControlFrame::ReflowTextControlChild(
     nsIFrame* aKid, nsPresContext* aPresContext,
     const ReflowInput& aReflowInput, nsReflowStatus& aStatus,
-    ReflowOutput& aParentDesiredSize, nscoord& aButtonBoxISize) {
+    ReflowOutput& aParentDesiredSize, const LogicalSize& aParentContentBoxSize,
+    nscoord& aButtonBoxISize) {
   const WritingMode outerWM = aReflowInput.GetWritingMode();
   // compute available size and frame offsets for child
   const WritingMode wm = aKid->GetWritingMode();
-  LogicalSize availSize = aReflowInput.ComputedSizeWithPadding(wm);
+  const auto parentPadding = aReflowInput.ComputedLogicalPadding(wm);
+  const LogicalSize contentBoxSize =
+      aParentContentBoxSize.ConvertTo(wm, outerWM);
+  const LogicalSize paddingBoxSize = contentBoxSize + parentPadding.Size(wm);
+  const LogicalSize borderBoxSize =
+      paddingBoxSize + aReflowInput.ComputedLogicalBorder(wm).Size(wm);
+  LogicalSize availSize = paddingBoxSize;
   availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
 
-  bool isButtonBox = IsButtonBox(aKid);
+  const bool isButtonBox = IsButtonBox(aKid);
 
   ReflowInput kidReflowInput(aPresContext, aReflowInput, aKid, availSize,
                              Nothing(), ReflowInput::InitFlag::CallerWillInit);
 
   // Override padding with our computed padding in case we got it from theming
   // or percentage, if we're not the button box.
-  auto overridePadding =
-      isButtonBox ? Nothing() : Some(aReflowInput.ComputedLogicalPadding(wm));
+  auto overridePadding = isButtonBox ? Nothing() : Some(parentPadding);
   if (!isButtonBox && aButtonBoxISize) {
     // Button box respects inline-end-padding, so we don't need to.
     overridePadding->IEnd(outerWM) = 0;
@@ -722,8 +687,7 @@ void nsTextControlFrame::ReflowTextControlChild(
   // We want to let our button box fill the frame in the block axis, up to the
   // edge of the control's border. So, we use the control's padding-box as the
   // containing block size for our button box.
-  auto overrideCBSize =
-      isButtonBox ? Some(aReflowInput.ComputedSizeWithPadding(wm)) : Nothing();
+  auto overrideCBSize = isButtonBox ? Some(paddingBoxSize) : Nothing();
   kidReflowInput.Init(aPresContext, overrideCBSize, Nothing(), overridePadding);
 
   LogicalPoint position(wm);
@@ -746,14 +710,12 @@ void nsTextControlFrame::ReflowTextControlChild(
     // the only exception, which has an auto size).
     kidReflowInput.SetComputedISize(
         std::max(0, aReflowInput.ComputedISize() - aButtonBoxISize));
-    kidReflowInput.SetComputedBSize(aReflowInput.ComputedBSize());
+    kidReflowInput.SetComputedBSize(contentBoxSize.BSize(wm));
   }
 
   // reflow the child
   ReflowOutput desiredSize(aReflowInput);
-  const nsSize containerSize =
-      aReflowInput.ComputedSizeWithBorderPadding(outerWM).GetPhysicalSize(
-          outerWM);
+  const nsSize containerSize = borderBoxSize.GetPhysicalSize(wm);
   ReflowChild(aKid, aPresContext, desiredSize, kidReflowInput, wm, position,
               containerSize, ReflowChildFlags::Default, aStatus);
 
@@ -767,7 +729,7 @@ void nsTextControlFrame::ReflowTextControlChild(
     buttonRect.ISize(outerWM) = size.ISize(outerWM);
     buttonRect.BStart(outerWM) =
         bp.BStart(outerWM) +
-        (aReflowInput.ComputedBSize() - size.BSize(outerWM)) / 2;
+        (aParentContentBoxSize.BSize(outerWM) - size.BSize(outerWM)) / 2;
     // Align to the inline-end of the content box.
     buttonRect.IStart(outerWM) =
         bp.IStart(outerWM) + aReflowInput.ComputedISize() - size.ISize(outerWM);
diff --git a/layout/forms/nsTextControlFrame.h b/layout/forms/nsTextControlFrame.h
index 0d52e5849f..2eb6f18d15 100644
--- a/layout/forms/nsTextControlFrame.h
+++ b/layout/forms/nsTextControlFrame.h
@@ -63,14 +63,6 @@ class nsTextControlFrame : public nsContainerFrame,
   nscoord GetMinISize(gfxContext* aRenderingContext) override;
   nscoord GetPrefISize(gfxContext* aRenderingContext) override;
 
-  mozilla::LogicalSize ComputeAutoSize(
-      gfxContext* aRenderingContext, mozilla::WritingMode aWM,
-      const mozilla::LogicalSize& aCBSize, nscoord aAvailableISize,
-      const mozilla::LogicalSize& aMargin,
-      const mozilla::LogicalSize& aBorderPadding,
-      const mozilla::StyleSizeOverrides& aSizeOverrides,
-      mozilla::ComputeSizeFlags aFlags) override;
-
   void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
               const ReflowInput& aReflowInput,
               nsReflowStatus& aStatus) override;
@@ -180,10 +172,11 @@ class nsTextControlFrame : public nsContainerFrame,
   /**
    * Launch the reflow on the child frames - see nsTextControlFrame::Reflow()
    */
-  void ReflowTextControlChild(nsIFrame* aFrame, nsPresContext* aPresContext,
+  void ReflowTextControlChild(nsIFrame* aKid, nsPresContext* aPresContext,
                               const ReflowInput& aReflowInput,
                               nsReflowStatus& aStatus,
                               ReflowOutput& aParentDesiredSize,
+                              const mozilla::LogicalSize& aParentContentBoxSize,
                               nscoord& aButtonBoxISize);
 
  public:
@@ -278,8 +271,7 @@ class nsTextControlFrame : public nsContainerFrame,
   // etc.  Just the size of our actual area for the text (and the scrollbars,
   // for <textarea>).
   mozilla::LogicalSize CalcIntrinsicSize(gfxContext* aRenderingContext,
-                                         mozilla::WritingMode aWM,
-                                         float aFontSizeInflation) const;
+                                         mozilla::WritingMode aWM) const;
 
  private:
   // helper methods
diff --git a/layout/generic/AspectRatio.cpp b/layout/generic/AspectRatio.cpp
index 2fe51fed5e..0a8ef181e4 100644
--- a/layout/generic/AspectRatio.cpp
+++ b/layout/generic/AspectRatio.cpp
@@ -20,7 +20,7 @@ nscoord AspectRatio::ComputeRatioDependentSize(
   const LogicalSize& boxSizingAdjust = mUseBoxSizing == UseBoxSizing::No
                                            ? LogicalSize(aWM)
                                            : aContentBoxSizeToBoxSizingAdjust;
-  return aRatioDependentAxis == LogicalAxis::eLogicalAxisInline
+  return aRatioDependentAxis == LogicalAxis::Inline
              ? ConvertToWritingMode(aWM).ApplyTo(aRatioDeterminingSize +
                                                  boxSizingAdjust.BSize(aWM)) -
                    boxSizingAdjust.ISize(aWM)
diff --git a/layout/generic/AspectRatio.h b/layout/generic/AspectRatio.h
index 6f48a07da3..daafd06ba8 100644
--- a/layout/generic/AspectRatio.h
+++ b/layout/generic/AspectRatio.h
@@ -22,7 +22,7 @@ struct ParamTraits;
 
 namespace mozilla {
 
-enum LogicalAxis : uint8_t;
+enum class LogicalAxis : uint8_t;
 class LogicalSize;
 class WritingMode;
 
diff --git a/layout/generic/BRFrame.cpp b/layout/generic/BRFrame.cpp
index 52cc3a0b46..13b3fbb9a4 100644
--- a/layout/generic/BRFrame.cpp
+++ b/layout/generic/BRFrame.cpp
@@ -98,7 +98,6 @@ void BRFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                      const ReflowInput& aReflowInput, nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("BRFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   WritingMode wm = aReflowInput.GetWritingMode();
@@ -186,18 +185,10 @@ void BRFrame::AddInlinePrefISize(gfxContext* aRenderingContext,
 }
 
 /* virtual */
-nscoord BRFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  return result;
-}
+nscoord BRFrame::GetMinISize(gfxContext* aRenderingContext) { return 0; }
 
 /* virtual */
-nscoord BRFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  return result;
-}
+nscoord BRFrame::GetPrefISize(gfxContext* aRenderingContext) { return 0; }
 
 Maybe<nscoord> BRFrame::GetNaturalBaselineBOffset(
     WritingMode aWM, BaselineSharingGroup aBaselineGroup,
diff --git a/layout/generic/CSSAlignUtils.cpp b/layout/generic/CSSAlignUtils.cpp
index b88ec8bfa4..7dd8999563 100644
--- a/layout/generic/CSSAlignUtils.cpp
+++ b/layout/generic/CSSAlignUtils.cpp
@@ -68,10 +68,10 @@ nscoord CSSAlignUtils::AlignJustifySelf(const StyleAlignFlags& aAlignment,
     // (Note: ReflowInput will have treated "auto" margins as 0, so we
     // don't need to do anything special to avoid expanding them.)
     hasAutoMarginStart = hasAutoMarginEnd = false;
-  } else if (aAxis == eLogicalAxisBlock) {
+  } else if (aAxis == LogicalAxis::Block) {
     hasAutoMarginStart = styleMargin.GetBStart(wm).IsAuto();
     hasAutoMarginEnd = styleMargin.GetBEnd(wm).IsAuto();
-  } else { /* aAxis == eLogicalAxisInline */
+  } else { /* aAxis == LogicalAxis::Inline */
     hasAutoMarginStart = styleMargin.GetIStart(wm).IsAuto();
     hasAutoMarginEnd = styleMargin.GetIEnd(wm).IsAuto();
   }
diff --git a/layout/generic/ColumnSetWrapperFrame.cpp b/layout/generic/ColumnSetWrapperFrame.cpp
index 7717f14df8..9f22222925 100644
--- a/layout/generic/ColumnSetWrapperFrame.cpp
+++ b/layout/generic/ColumnSetWrapperFrame.cpp
@@ -151,7 +151,6 @@ void ColumnSetWrapperFrame::MarkIntrinsicISizesDirty() {
 
 nscoord ColumnSetWrapperFrame::GetMinISize(gfxContext* aRenderingContext) {
   nscoord iSize = 0;
-  DISPLAY_MIN_INLINE_SIZE(this, iSize);
 
   if (Maybe<nscoord> containISize =
           ContainIntrinsicISize(NS_UNCONSTRAINEDSIZE)) {
@@ -193,7 +192,6 @@ nscoord ColumnSetWrapperFrame::GetMinISize(gfxContext* aRenderingContext) {
 
 nscoord ColumnSetWrapperFrame::GetPrefISize(gfxContext* aRenderingContext) {
   nscoord iSize = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, iSize);
 
   if (Maybe<nscoord> containISize =
           ContainIntrinsicISize(NS_UNCONSTRAINEDSIZE)) {
diff --git a/layout/generic/MiddleCroppingBlockFrame.cpp b/layout/generic/MiddleCroppingBlockFrame.cpp
index 4cbbb684aa..75dc205a4f 100644
--- a/layout/generic/MiddleCroppingBlockFrame.cpp
+++ b/layout/generic/MiddleCroppingBlockFrame.cpp
@@ -57,18 +57,11 @@ void MiddleCroppingBlockFrame::UpdateDisplayedValueToUncroppedValue(
 }
 
 nscoord MiddleCroppingBlockFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-
   // Our min inline size is our pref inline size
-  result = GetPrefISize(aRenderingContext);
-  return result;
+  return GetPrefISize(aRenderingContext);
 }
 
 nscoord MiddleCroppingBlockFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
   nsAutoString prevValue;
   bool restoreOldValue = false;
 
@@ -79,7 +72,7 @@ nscoord MiddleCroppingBlockFrame::GetPrefISize(gfxContext* aRenderingContext) {
     UpdateDisplayedValueToUncroppedValue(false);
   }
 
-  result = nsBlockFrame::GetPrefISize(aRenderingContext);
+  nscoord result = nsBlockFrame::GetPrefISize(aRenderingContext);
 
   if (restoreOldValue) {
     UpdateDisplayedValue(prevValue, /* aIsCropped = */ true, false);
diff --git a/layout/generic/PrintedSheetFrame.cpp b/layout/generic/PrintedSheetFrame.cpp
index 5b8151bbd0..384e63e361 100644
--- a/layout/generic/PrintedSheetFrame.cpp
+++ b/layout/generic/PrintedSheetFrame.cpp
@@ -86,7 +86,6 @@ void PrintedSheetFrame::Reflow(nsPresContext* aPresContext,
                                nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("PrintedSheetFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // If we have a prev-in-flow, take its overflowing content:
diff --git a/layout/generic/ReflowInput.cpp b/layout/generic/ReflowInput.cpp
index ed7dbd2656..c642c77b2c 100644
--- a/layout/generic/ReflowInput.cpp
+++ b/layout/generic/ReflowInput.cpp
@@ -13,10 +13,8 @@
 #include "CounterStyleManager.h"
 #include "LayoutLogging.h"
 #include "mozilla/dom/HTMLInputElement.h"
-#include "mozilla/StaticPrefs_layout.h"
 #include "mozilla/WritingModes.h"
 #include "nsBlockFrame.h"
-#include "nsCSSAnonBoxes.h"
 #include "nsFlexContainerFrame.h"
 #include "nsFontInflationData.h"
 #include "nsFontMetrics.h"
@@ -31,7 +29,6 @@
 #include "nsLineBox.h"
 #include "nsPresContext.h"
 #include "nsStyleConsts.h"
-#include "nsTableCellFrame.h"
 #include "nsTableFrame.h"
 #include "StickyScrollContainer.h"
 
@@ -1238,11 +1235,11 @@ static bool AxisPolarityFlipped(LogicalAxis aThisAxis, WritingMode aThisWm,
 }
 
 static bool InlinePolarityFlipped(WritingMode aThisWm, WritingMode aOtherWm) {
-  return AxisPolarityFlipped(eLogicalAxisInline, aThisWm, aOtherWm);
+  return AxisPolarityFlipped(LogicalAxis::Inline, aThisWm, aOtherWm);
 }
 
 static bool BlockPolarityFlipped(WritingMode aThisWm, WritingMode aOtherWm) {
-  return AxisPolarityFlipped(eLogicalAxisBlock, aThisWm, aOtherWm);
+  return AxisPolarityFlipped(LogicalAxis::Block, aThisWm, aOtherWm);
 }
 
 // Calculate the position of the hypothetical box that the element would have
@@ -1292,7 +1289,6 @@ void ReflowInput::CalculateHypotheticalPosition(
     // For non-replaced inline-level elements the 'inline size' property
     // doesn't apply, so we don't know what the inline size would have
     // been without reflowing it
-
   } else {
     // It's either a replaced inline-level element or a block-level element
 
@@ -1301,17 +1297,17 @@ void ReflowInput::CalculateHypotheticalPosition(
     // been in the flow. Note that we ignore any 'auto' and 'inherit'
     // values
     nscoord insideBoxISizing, outsideBoxISizing;
-    CalculateBorderPaddingMargin(eLogicalAxisInline, blockContentSize.ISize(wm),
-                                 &insideBoxISizing, &outsideBoxISizing);
+    CalculateBorderPaddingMargin(LogicalAxis::Inline,
+                                 blockContentSize.ISize(wm), &insideBoxISizing,
+                                 &outsideBoxISizing);
 
     if (mFlags.mIsReplaced && isAutoISize) {
-      // It's a replaced element with an 'auto' inline size so the box
-      // inline size is its intrinsic size plus any border/padding/margin
+      // It's a replaced element with an 'auto' inline size so the box inline
+      // size is its intrinsic size plus any border/padding/margin
       if (intrinsicSize) {
         boxISize.emplace(LogicalSize(wm, *intrinsicSize).ISize(wm) +
                          outsideBoxISizing + insideBoxISizing);
       }
-
     } else if (isAutoISize) {
       // The box inline size is the containing block inline size
       boxISize.emplace(blockContentSize.ISize(wm));
@@ -1320,7 +1316,7 @@ void ReflowInput::CalculateHypotheticalPosition(
       // percentage based this computed value may be different from the computed
       // value calculated using the absolute containing block width
       nscoord insideBoxBSizing, dummy;
-      CalculateBorderPaddingMargin(eLogicalAxisBlock,
+      CalculateBorderPaddingMargin(LogicalAxis::Block,
                                    blockContentSize.ISize(wm),
                                    &insideBoxBSizing, &dummy);
       boxISize.emplace(
@@ -1500,7 +1496,7 @@ void ReflowInput::CalculateHypotheticalPosition(
     // been in the flow. Note that we ignore any 'auto' and 'inherit'
     // values.
     nscoord insideBoxSizing, outsideBoxSizing;
-    CalculateBorderPaddingMargin(eLogicalAxisBlock, blockContentSize.BSize(wm),
+    CalculateBorderPaddingMargin(LogicalAxis::Block, blockContentSize.BSize(wm),
                                  &insideBoxSizing, &outsideBoxSizing);
 
     nscoord boxBSize;
@@ -1627,7 +1623,7 @@ LogicalSize ReflowInput::CalculateAbsoluteSizeWithResolvedAutoBlockSize(
           : LogicalSize(wm);
   auto transferredISize =
       mStylePosition->mAspectRatio.ToLayoutRatio().ComputeRatioDependentSize(
-          LogicalAxis::eLogicalAxisInline, wm, aAutoBSize, boxSizingAdjust);
+          LogicalAxis::Inline, wm, aAutoBSize, boxSizingAdjust);
   resultSize.ISize(wm) = ApplyMinMaxISize(transferredISize);
 
   MOZ_ASSERT(mFlags.mIsBSizeSetByAspectRatio,
@@ -2167,8 +2163,6 @@ void ReflowInput::InitConstraints(
   WritingMode wm = GetWritingMode();
   LogicalSize cbSize = aContainingBlockSize.valueOr(
       LogicalSize(mWritingMode, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE));
-  DISPLAY_INIT_CONSTRAINTS(mFrame, this, cbSize.ISize(wm), cbSize.BSize(wm),
-                           aBorder, aPadding);
 
   // If this is a reflow root, then set the computed width and
   // height equal to the available space
@@ -2239,7 +2233,7 @@ void ReflowInput::InitConstraints(
         // eStyleUnit_Auto;" used to be called exclusively.
         if (mFlags.mIsReplaced && mStyleDisplay->IsInlineOutsideStyle()) {
           // Get the containing block's reflow input
-          NS_ASSERTION(nullptr != cbri, "no containing block");
+          NS_ASSERTION(cbri, "no containing block");
           // in quirks mode, get the cb height using the special quirk method
           if (!wm.IsVertical() &&
               eCompatibility_NavQuirks == aPresContext->CompatibilityMode()) {
@@ -2359,46 +2353,79 @@ void ReflowInput::InitConstraints(
     } else {
       AutoMaybeDisableFontInflation an(mFrame);
 
-      const bool isBlockLevel =
-          ((!mStyleDisplay->IsInlineOutsideStyle() &&
-            // internal table values on replaced elements behaves as inline
-            // https://drafts.csswg.org/css-tables-3/#table-structure
-            // "... it is handled instead as though the author had declared
-            //  either 'block' (for 'table' display) or 'inline' (for all
-            //  other values)"
-            !(mFlags.mIsReplaced && (mStyleDisplay->IsInnerTableStyle() ||
-                                     mStyleDisplay->DisplayOutside() ==
-                                         StyleDisplayOutside::TableCaption))) ||
-           // The inner table frame always fills its outer wrapper table frame,
-           // even for 'inline-table'.
-           mFrame->IsTableFrame()) &&
-          // XXX abs.pos. continuations treated like blocks, see comment in
-          // the else-if condition above.
-          (!mFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW) ||
-           mStyleDisplay->IsAbsolutelyPositionedStyle());
-
-      if (!isBlockLevel) {
-        mComputeSizeFlags += ComputeSizeFlag::ShrinkWrap;
-      }
+      nsIFrame* const alignCB = [&] {
+        nsIFrame* cb = mFrame->GetParent();
+        if (cb->IsTableWrapperFrame()) {
+          nsIFrame* alignCBParent = cb->GetParent();
+          if (alignCBParent && alignCBParent->IsGridContainerFrame()) {
+            return alignCBParent;
+          }
+        }
+        return cb;
+      }();
 
-      nsIFrame* alignCB = mFrame->GetParent();
-      if (alignCB->IsTableWrapperFrame()) {
-        nsIFrame* alignCBParent = alignCB->GetParent();
-        if (alignCBParent && alignCBParent->IsGridContainerFrame()) {
-          alignCB = alignCBParent;
+      const bool isInlineLevel = [&] {
+        if (mFrame->IsTableFrame()) {
+          // An inner table frame is not inline-level, even if it happens to
+          // have 'display:inline-table'. (That makes its table-wrapper frame be
+          // inline-level, but not the inner table frame)
+          return false;
         }
-      }
-      if (!alignCB->IsGridContainerFrame()) {
-        // Shrink-wrap blocks that are orthogonal to their container.
-        if (isBlockLevel && mCBReflowInput &&
+        if (mStyleDisplay->IsInlineOutsideStyle()) {
+          return true;
+        }
+        if (mFlags.mIsReplaced && (mStyleDisplay->IsInnerTableStyle() ||
+                                   mStyleDisplay->DisplayOutside() ==
+                                       StyleDisplayOutside::TableCaption)) {
+          // Internal table values on replaced elements behave as inline
+          // https://drafts.csswg.org/css-tables-3/#table-structure
+          //
+          //     ... it is handled instead as though the author had declared
+          //     either 'block' (for 'table' display) or 'inline' (for all
+          //     other values)"
+          //
+          // FIXME(emilio): The only test that covers this is
+          // table-anonymous-objects-211.xht, which fails on other browsers (but
+          // differently to us, if you just remove this condition).
+          return true;
+        }
+        if (mFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW) &&
+            !mStyleDisplay->IsAbsolutelyPositionedStyle()) {
+          // Floats are treated as inline-level and also shrink-wrap.
+          return true;
+        }
+        return false;
+      }();
+
+      const bool shouldShrinkWrap = [&] {
+        if (isInlineLevel) {
+          return true;
+        }
+        if (mFlags.mIsReplaced && !alignCB->IsFlexOrGridContainer()) {
+          // Shrink-wrap replaced elements when in-flow (out of flows are
+          // handled above). We exclude replaced elements in grid or flex
+          // contexts, where we don't want to shrink-wrap unconditionally (so
+          // that stretching can happen). When grid/flex explicitly want
+          // shrink-wrapping, they can request it directly using the relevant
+          // flag.
+          return true;
+        }
+        if (!alignCB->IsGridContainerFrame() && mCBReflowInput &&
             mCBReflowInput->GetWritingMode().IsOrthogonalTo(mWritingMode)) {
-          mComputeSizeFlags += ComputeSizeFlag::ShrinkWrap;
+          // Shrink-wrap blocks that are orthogonal to their container (unless
+          // we're in a grid?)
+          return true;
         }
+        return false;
+      }();
+
+      if (shouldShrinkWrap) {
+        mComputeSizeFlags += ComputeSizeFlag::ShrinkWrap;
       }
 
       if (cbSize.ISize(wm) == NS_UNCONSTRAINEDSIZE) {
-        // For orthogonal flows, where we found a parent orthogonal-limit
-        // for AvailableISize() in Init(), we'll use the same here as well.
+        // For orthogonal flows, where we found a parent orthogonal-limit for
+        // AvailableISize() in Init(), we'll use the same here as well.
         cbSize.ISize(wm) = AvailableISize();
       }
 
@@ -2418,10 +2445,7 @@ void ReflowInput::InitConstraints(
           size.mAspectRatioUsage == nsIFrame::AspectRatioUsage::ToComputeBSize;
 
       const bool shouldCalculateBlockSideMargins = [&]() {
-        if (!isBlockLevel) {
-          return false;
-        }
-        if (mStyleDisplay->mDisplay == StyleDisplay::InlineTable) {
+        if (isInlineLevel) {
           return false;
         }
         if (mFrame->IsTableFrame()) {
@@ -2475,7 +2499,6 @@ void SizeComputationInput::InitOffsets(WritingMode aCBWM, nscoord aPercentBasis,
                                        const Maybe<LogicalMargin>& aBorder,
                                        const Maybe<LogicalMargin>& aPadding,
                                        const nsStyleDisplay* aDisplay) {
-  DISPLAY_INIT_OFFSETS(mFrame, this, aPercentBasis, aCBWM, aBorder, aPadding);
   nsPresContext* presContext = mFrame->PresContext();
 
   // Compute margins from the specified margin style information. These
@@ -2533,7 +2556,7 @@ void SizeComputationInput::InitOffsets(WritingMode aCBWM, nscoord aPercentBasis,
       }
       mComputedPadding.Side(side, wm) += val;
       needPaddingProp = true;
-      if (aAxis == eLogicalAxisBlock && val > 0) {
+      if (aAxis == LogicalAxis::Block && val > 0) {
         // We have a baseline-adjusted block-axis start padding, so
         // we need this to mark lines dirty when mIsBResize is true:
         this->mFrame->AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
@@ -2541,10 +2564,10 @@ void SizeComputationInput::InitOffsets(WritingMode aCBWM, nscoord aPercentBasis,
     }
   };
   if (!aFlags.contains(ComputeSizeFlag::IsGridMeasuringReflow)) {
-    ApplyBaselinePadding(eLogicalAxisBlock, nsIFrame::BBaselinePadProperty());
+    ApplyBaselinePadding(LogicalAxis::Block, nsIFrame::BBaselinePadProperty());
   }
   if (!aFlags.contains(ComputeSizeFlag::ShrinkWrap)) {
-    ApplyBaselinePadding(eLogicalAxisInline, nsIFrame::IBaselinePadProperty());
+    ApplyBaselinePadding(LogicalAxis::Inline, nsIFrame::IBaselinePadProperty());
   }
 
   LogicalMargin border(wm);
diff --git a/layout/generic/ReflowInput.h b/layout/generic/ReflowInput.h
index 620ad0f413..ba49edcaf6 100644
--- a/layout/generic/ReflowInput.h
+++ b/layout/generic/ReflowInput.h
@@ -178,20 +178,6 @@ struct SizeComputationInput {
                        const mozilla::Maybe<mozilla::LogicalMargin>& aPadding =
                            mozilla::Nothing());
 
-#ifdef DEBUG
-  // Reflow trace methods.  Defined in nsFrame.cpp so they have access
-  // to the display-reflow infrastructure.
-  static void* DisplayInitOffsetsEnter(nsIFrame* aFrame,
-                                       SizeComputationInput* aState,
-                                       nscoord aPercentBasis,
-                                       mozilla::WritingMode aCBWritingMode,
-                                       const nsMargin* aBorder,
-                                       const nsMargin* aPadding);
-  static void DisplayInitOffsetsExit(nsIFrame* aFrame,
-                                     SizeComputationInput* aState,
-                                     void* aValue);
-#endif
-
  private:
   /**
    * Computes margin values from the specified margin style information, and
@@ -367,6 +353,16 @@ struct ReflowInput : public SizeComputationInput {
 
   mozilla::LogicalSize AvailableSize() const { return mAvailableSize; }
   mozilla::LogicalSize ComputedSize() const { return mComputedSize; }
+
+  template <typename F>
+  mozilla::LogicalSize ComputedSizeWithBSizeFallback(F&& aFallback) const {
+    auto size = mComputedSize;
+    if (size.BSize(mWritingMode) == NS_UNCONSTRAINEDSIZE) {
+      size.BSize(mWritingMode) = ApplyMinMaxBSize(aFallback());
+    }
+    return size;
+  }
+
   mozilla::LogicalSize ComputedMinSize() const { return mComputedMinSize; }
   mozilla::LogicalSize ComputedMaxSize() const { return mComputedMaxSize; }
 
@@ -888,21 +884,6 @@ struct ReflowInput : public SizeComputationInput {
                                             LogicalMargin& aMargin,
                                             LogicalMargin& aOffsets);
 
-#ifdef DEBUG
-  // Reflow trace methods.  Defined in nsFrame.cpp so they have access
-  // to the display-reflow infrastructure.
-  static void* DisplayInitConstraintsEnter(nsIFrame* aFrame,
-                                           ReflowInput* aState,
-                                           nscoord aCBISize, nscoord aCBBSize,
-                                           const nsMargin* aBorder,
-                                           const nsMargin* aPadding);
-  static void DisplayInitConstraintsExit(nsIFrame* aFrame, ReflowInput* aState,
-                                         void* aValue);
-  static void* DisplayInitFrameTypeEnter(nsIFrame* aFrame, ReflowInput* aState);
-  static void DisplayInitFrameTypeExit(nsIFrame* aFrame, ReflowInput* aState,
-                                       void* aValue);
-#endif
-
  protected:
   void InitCBReflowInput();
   void InitResizeFlags(nsPresContext* aPresContext,
diff --git a/layout/generic/ScrollGeneration.h b/layout/generic/ScrollGeneration.h
index 90eb243e9e..5f14844e33 100644
--- a/layout/generic/ScrollGeneration.h
+++ b/layout/generic/ScrollGeneration.h
@@ -7,6 +7,7 @@
 
 #include <cstdint>
 #include <iosfwd>
+#include <tuple>
 
 namespace mozilla {
 
@@ -23,7 +24,7 @@ std::ostream& operator<<(std::ostream& aStream,
                          const ScrollGeneration<Tag>& aGen);
 
 template <typename Tag>
-struct ScrollGeneration {
+struct ScrollGeneration final {
   friend struct ScrollGenerationCounter;
 
  private:
@@ -43,6 +44,8 @@ struct ScrollGeneration {
   friend std::ostream& operator<< <>(std::ostream& aStream,
                                      const ScrollGeneration<Tag>& aGen);
 
+  auto MutTiedFields() { return std::tie(mValue); }
+
  private:
   uint64_t mValue;
 };
diff --git a/layout/generic/ScrollSnapTargetId.h b/layout/generic/ScrollSnapTargetId.h
index f53e736fa1..a4a281f5e7 100644
--- a/layout/generic/ScrollSnapTargetId.h
+++ b/layout/generic/ScrollSnapTargetId.h
@@ -17,6 +17,7 @@ namespace mozilla {
 enum class ScrollSnapTargetId : uintptr_t {
   None = 0,
 };
+inline constexpr bool IsEnumCase(ScrollSnapTargetId) { return true; }
 
 struct ScrollSnapTargetIds {
   CopyableTArray<ScrollSnapTargetId> mIdsOnX;
diff --git a/layout/generic/ViewportFrame.cpp b/layout/generic/ViewportFrame.cpp
index 812aaa8e33..d71842d013 100644
--- a/layout/generic/ViewportFrame.cpp
+++ b/layout/generic/ViewportFrame.cpp
@@ -271,26 +271,16 @@ void ViewportFrame::RemoveFrame(DestroyContext& aContext, ChildListID aListID,
 
 /* virtual */
 nscoord ViewportFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  if (mFrames.IsEmpty())
-    result = 0;
-  else
-    result = mFrames.FirstChild()->GetMinISize(aRenderingContext);
-
-  return result;
+  return mFrames.IsEmpty()
+             ? 0
+             : mFrames.FirstChild()->GetMinISize(aRenderingContext);
 }
 
 /* virtual */
 nscoord ViewportFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  if (mFrames.IsEmpty())
-    result = 0;
-  else
-    result = mFrames.FirstChild()->GetPrefISize(aRenderingContext);
-
-  return result;
+  return mFrames.IsEmpty()
+             ? 0
+             : mFrames.FirstChild()->GetPrefISize(aRenderingContext);
 }
 
 nsPoint ViewportFrame::AdjustReflowInputForScrollbars(
@@ -330,7 +320,6 @@ void ViewportFrame::Reflow(nsPresContext* aPresContext,
                            nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("ViewportFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE_REFLOW_IN("ViewportFrame::Reflow");
 
diff --git a/layout/generic/WritingModes.h b/layout/generic/WritingModes.h
index e84c5e276d..0fcf47f1d0 100644
--- a/layout/generic/WritingModes.h
+++ b/layout/generic/WritingModes.h
@@ -46,20 +46,22 @@ struct IMENotification;
 }  // namespace widget
 
 // Logical axis, edge, side and corner constants for use in various places.
-enum LogicalAxis : uint8_t {
-  eLogicalAxisBlock = 0x0,
-  eLogicalAxisInline = 0x1
+enum class LogicalAxis : uint8_t {
+  Block,
+  Inline,
 };
 enum LogicalEdge { eLogicalEdgeStart = 0x0, eLogicalEdgeEnd = 0x1 };
-enum LogicalSide : uint8_t {
-  eLogicalSideBStart = (eLogicalAxisBlock << 1) | eLogicalEdgeStart,   // 0x0
-  eLogicalSideBEnd = (eLogicalAxisBlock << 1) | eLogicalEdgeEnd,       // 0x1
-  eLogicalSideIStart = (eLogicalAxisInline << 1) | eLogicalEdgeStart,  // 0x2
-  eLogicalSideIEnd = (eLogicalAxisInline << 1) | eLogicalEdgeEnd       // 0x3
+
+enum class LogicalSide : uint8_t {
+  BStart,
+  BEnd,
+  IStart,
+  IEnd,
 };
+
 constexpr auto AllLogicalSides() {
-  return mozilla::MakeInclusiveEnumeratedRange(eLogicalSideBStart,
-                                               eLogicalSideIEnd);
+  return mozilla::MakeInclusiveEnumeratedRange(LogicalSide::BStart,
+                                               LogicalSide::IEnd);
 }
 
 enum class LogicalCorner : uint8_t {
@@ -82,16 +84,23 @@ enum class PhysicalAxes : uint8_t {
 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(PhysicalAxes)
 
 inline LogicalAxis GetOrthogonalAxis(LogicalAxis aAxis) {
-  return aAxis == eLogicalAxisBlock ? eLogicalAxisInline : eLogicalAxisBlock;
+  return aAxis == LogicalAxis::Block ? LogicalAxis::Inline : LogicalAxis::Block;
+}
+
+inline bool IsInline(LogicalSide aSide) {
+  return (aSide == LogicalSide::IStart) || (aSide == LogicalSide::IEnd);
 }
 
-inline bool IsInline(LogicalSide aSide) { return aSide & 0x2; }
 inline bool IsBlock(LogicalSide aSide) { return !IsInline(aSide); }
-inline bool IsEnd(LogicalSide aSide) { return aSide & 0x1; }
+
+inline bool IsEnd(LogicalSide aSide) {
+  return (aSide == LogicalSide::BEnd) || (aSide == LogicalSide::IEnd);
+}
+
 inline bool IsStart(LogicalSide aSide) { return !IsEnd(aSide); }
 
 inline LogicalAxis GetAxis(LogicalSide aSide) {
-  return IsInline(aSide) ? eLogicalAxisInline : eLogicalAxisBlock;
+  return IsInline(aSide) ? LogicalAxis::Inline : LogicalAxis::Block;
 }
 
 inline LogicalEdge GetEdge(LogicalSide aSide) {
@@ -104,7 +113,7 @@ inline LogicalEdge GetOppositeEdge(LogicalEdge aEdge) {
 }
 
 inline LogicalSide MakeLogicalSide(LogicalAxis aAxis, LogicalEdge aEdge) {
-  return LogicalSide((aAxis << 1) | aEdge);
+  return LogicalSide((uint8_t(aAxis) << 1) | aEdge);
 }
 
 inline LogicalSide GetOppositeSide(LogicalSide aSide) {
@@ -113,20 +122,20 @@ inline LogicalSide GetOppositeSide(LogicalSide aSide) {
 
 enum LogicalSideBits {
   eLogicalSideBitsNone = 0,
-  eLogicalSideBitsBStart = 1 << eLogicalSideBStart,
-  eLogicalSideBitsBEnd = 1 << eLogicalSideBEnd,
-  eLogicalSideBitsIEnd = 1 << eLogicalSideIEnd,
-  eLogicalSideBitsIStart = 1 << eLogicalSideIStart,
+  eLogicalSideBitsBStart = 1 << static_cast<uint8_t>(LogicalSide::BStart),
+  eLogicalSideBitsBEnd = 1 << static_cast<uint8_t>(LogicalSide::BEnd),
+  eLogicalSideBitsIEnd = 1 << static_cast<uint8_t>(LogicalSide::IEnd),
+  eLogicalSideBitsIStart = 1 << static_cast<uint8_t>(LogicalSide::IStart),
   eLogicalSideBitsBBoth = eLogicalSideBitsBStart | eLogicalSideBitsBEnd,
   eLogicalSideBitsIBoth = eLogicalSideBitsIStart | eLogicalSideBitsIEnd,
   eLogicalSideBitsAll = eLogicalSideBitsBBoth | eLogicalSideBitsIBoth
 };
 
 enum LineRelativeDir {
-  eLineRelativeDirOver = eLogicalSideBStart,
-  eLineRelativeDirUnder = eLogicalSideBEnd,
-  eLineRelativeDirLeft = eLogicalSideIStart,
-  eLineRelativeDirRight = eLogicalSideIEnd
+  eLineRelativeDirOver = static_cast<uint8_t>(LogicalSide::BStart),
+  eLineRelativeDirUnder = static_cast<uint8_t>(LogicalSide::BEnd),
+  eLineRelativeDirLeft = static_cast<uint8_t>(LogicalSide::IStart),
+  eLineRelativeDirRight = static_cast<uint8_t>(LogicalSide::IEnd)
 };
 
 /**
@@ -329,11 +338,12 @@ class WritingMode {
     static_assert(uint8_t(StyleWritingModeProperty::HorizontalTb) == 0 &&
                       uint8_t(StyleWritingModeProperty::VerticalRl) == 1 &&
                       uint8_t(StyleWritingModeProperty::VerticalLr) == 3 &&
-                      eLogicalAxisBlock == 0 && eLogicalAxisInline == 1 &&
-                      eAxisVertical == 0 && eAxisHorizontal == 1,
+                      uint8_t(LogicalAxis::Block) == 0 &&
+                      uint8_t(LogicalAxis::Inline) == 1 && eAxisVertical == 0 &&
+                      eAxisHorizontal == 1,
                   "unexpected writing-mode, logical axis or physical axis "
                   "constant values");
-    return mozilla::PhysicalAxis((aWritingModeValue ^ aAxis) & 0x1);
+    return mozilla::PhysicalAxis((aWritingModeValue ^ uint8_t(aAxis)) & 0x1);
   }
 
   mozilla::PhysicalAxis PhysicalAxis(LogicalAxis aAxis) const {
@@ -445,38 +455,38 @@ class WritingMode {
     static const LogicalSide kPhysicalToLogicalSides[][4] = {
       // top                right
       // bottom             left
-      { eLogicalSideBStart, eLogicalSideIEnd,
-        eLogicalSideBEnd,   eLogicalSideIStart },  // horizontal-tb         ltr
-      { eLogicalSideIStart, eLogicalSideBStart,
-        eLogicalSideIEnd,   eLogicalSideBEnd   },  // vertical-rl           ltr
-      { eLogicalSideBStart, eLogicalSideIStart,
-        eLogicalSideBEnd,   eLogicalSideIEnd   },  // horizontal-tb         rtl
-      { eLogicalSideIEnd,   eLogicalSideBStart,
-        eLogicalSideIStart, eLogicalSideBEnd   },  // vertical-rl           rtl
-      { eLogicalSideBEnd,   eLogicalSideIStart,
-        eLogicalSideBStart, eLogicalSideIEnd   },  // (horizontal-bt) (inv) ltr
-      { eLogicalSideIStart, eLogicalSideBEnd,
-        eLogicalSideIEnd,   eLogicalSideBStart },  // vertical-lr   sw-left rtl
-      { eLogicalSideBEnd,   eLogicalSideIEnd,
-        eLogicalSideBStart, eLogicalSideIStart },  // (horizontal-bt) (inv) rtl
-      { eLogicalSideIEnd,   eLogicalSideBEnd,
-        eLogicalSideIStart, eLogicalSideBStart },  // vertical-lr   sw-left ltr
-      { eLogicalSideBStart, eLogicalSideIEnd,
-        eLogicalSideBEnd,   eLogicalSideIStart },  // horizontal-tb   (inv) rtl
-      { eLogicalSideIStart, eLogicalSideBStart,
-        eLogicalSideIEnd,   eLogicalSideBEnd   },  // vertical-rl   sw-left rtl
-      { eLogicalSideBStart, eLogicalSideIStart,
-        eLogicalSideBEnd,   eLogicalSideIEnd   },  // horizontal-tb   (inv) ltr
-      { eLogicalSideIEnd,   eLogicalSideBStart,
-        eLogicalSideIStart, eLogicalSideBEnd   },  // vertical-rl   sw-left ltr
-      { eLogicalSideBEnd,   eLogicalSideIEnd,
-        eLogicalSideBStart, eLogicalSideIStart },  // (horizontal-bt)       ltr
-      { eLogicalSideIStart, eLogicalSideBEnd,
-        eLogicalSideIEnd,   eLogicalSideBStart },  // vertical-lr           ltr
-      { eLogicalSideBEnd,   eLogicalSideIStart,
-        eLogicalSideBStart, eLogicalSideIEnd   },  // (horizontal-bt)       rtl
-      { eLogicalSideIEnd,   eLogicalSideBEnd,
-        eLogicalSideIStart, eLogicalSideBStart },  // vertical-lr           rtl
+      { LogicalSide::BStart, LogicalSide::IEnd,
+        LogicalSide::BEnd,   LogicalSide::IStart },  // horizontal-tb         ltr
+      { LogicalSide::IStart, LogicalSide::BStart,
+        LogicalSide::IEnd,   LogicalSide::BEnd   },  // vertical-rl           ltr
+      { LogicalSide::BStart, LogicalSide::IStart,
+        LogicalSide::BEnd,   LogicalSide::IEnd   },  // horizontal-tb         rtl
+      { LogicalSide::IEnd,   LogicalSide::BStart,
+        LogicalSide::IStart, LogicalSide::BEnd   },  // vertical-rl           rtl
+      { LogicalSide::BEnd,   LogicalSide::IStart,
+        LogicalSide::BStart, LogicalSide::IEnd   },  // (horizontal-bt) (inv) ltr
+      { LogicalSide::IStart, LogicalSide::BEnd,
+        LogicalSide::IEnd,   LogicalSide::BStart },  // vertical-lr   sw-left rtl
+      { LogicalSide::BEnd,   LogicalSide::IEnd,
+        LogicalSide::BStart, LogicalSide::IStart },  // (horizontal-bt) (inv) rtl
+      { LogicalSide::IEnd,   LogicalSide::BEnd,
+        LogicalSide::IStart, LogicalSide::BStart },  // vertical-lr   sw-left ltr
+      { LogicalSide::BStart, LogicalSide::IEnd,
+        LogicalSide::BEnd,   LogicalSide::IStart },  // horizontal-tb   (inv) rtl
+      { LogicalSide::IStart, LogicalSide::BStart,
+        LogicalSide::IEnd,   LogicalSide::BEnd   },  // vertical-rl   sw-left rtl
+      { LogicalSide::BStart, LogicalSide::IStart,
+        LogicalSide::BEnd,   LogicalSide::IEnd   },  // horizontal-tb   (inv) ltr
+      { LogicalSide::IEnd,   LogicalSide::BStart,
+        LogicalSide::IStart, LogicalSide::BEnd   },  // vertical-rl   sw-left ltr
+      { LogicalSide::BEnd,   LogicalSide::IEnd,
+        LogicalSide::BStart, LogicalSide::IStart },  // (horizontal-bt)       ltr
+      { LogicalSide::IStart, LogicalSide::BEnd,
+        LogicalSide::IEnd,   LogicalSide::BStart },  // vertical-lr           ltr
+      { LogicalSide::BEnd,   LogicalSide::IStart,
+        LogicalSide::BStart, LogicalSide::IEnd   },  // (horizontal-bt)       rtl
+      { LogicalSide::IEnd,   LogicalSide::BEnd,
+        LogicalSide::IStart, LogicalSide::BStart },  // vertical-lr           rtl
     };
     // clang-format on
 
@@ -732,7 +742,7 @@ class LogicalPoint {
     return mPoint.y;
   }
   nscoord Pos(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? I(aWM) : B(aWM);
+    return aAxis == LogicalAxis::Inline ? I(aWM) : B(aWM);
   }
   nscoord LineRelative(WritingMode aWritingMode,
                        const nsSize& aContainerSize) const  // line-axis
@@ -761,7 +771,7 @@ class LogicalPoint {
     return mPoint.y;
   }
   nscoord& Pos(LogicalAxis aAxis, WritingMode aWM) {
-    return aAxis == eLogicalAxisInline ? I(aWM) : B(aWM);
+    return aAxis == LogicalAxis::Inline ? I(aWM) : B(aWM);
   }
 
   /**
@@ -952,7 +962,7 @@ class LogicalSize {
     return mSize.height;
   }
   nscoord Size(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
+    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
   }
 
   nscoord Width(WritingMode aWritingMode) const {
@@ -978,7 +988,7 @@ class LogicalSize {
     return mSize.height;
   }
   nscoord& Size(LogicalAxis aAxis, WritingMode aWM) {
-    return aAxis == eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
+    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
   }
 
   /**
@@ -1234,10 +1244,10 @@ class LogicalMargin {
     return mMargin.bottom;
   }
   nscoord Start(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? IStart(aWM) : BStart(aWM);
+    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
   }
   nscoord End(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? IEnd(aWM) : BEnd(aWM);
+    return aAxis == LogicalAxis::Inline ? IEnd(aWM) : BEnd(aWM);
   }
 
   nscoord& IStart(WritingMode aWritingMode)  // inline-start margin
@@ -1261,10 +1271,10 @@ class LogicalMargin {
     return mMargin.bottom;
   }
   nscoord& Start(LogicalAxis aAxis, WritingMode aWM) {
-    return aAxis == eLogicalAxisInline ? IStart(aWM) : BStart(aWM);
+    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
   }
   nscoord& End(LogicalAxis aAxis, WritingMode aWM) {
-    return aAxis == eLogicalAxisInline ? IEnd(aWM) : BEnd(aWM);
+    return aAxis == LogicalAxis::Inline ? IEnd(aWM) : BEnd(aWM);
   }
 
   nscoord IStartEnd(WritingMode aWritingMode) const  // inline margins
@@ -1278,18 +1288,18 @@ class LogicalMargin {
     return mMargin.TopBottom();
   }
   nscoord StartEnd(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? IStartEnd(aWM) : BStartEnd(aWM);
+    return aAxis == LogicalAxis::Inline ? IStartEnd(aWM) : BStartEnd(aWM);
   }
 
   nscoord Side(LogicalSide aSide, WritingMode aWM) const {
     switch (aSide) {
-      case eLogicalSideBStart:
+      case LogicalSide::BStart:
         return BStart(aWM);
-      case eLogicalSideBEnd:
+      case LogicalSide::BEnd:
         return BEnd(aWM);
-      case eLogicalSideIStart:
+      case LogicalSide::IStart:
         return IStart(aWM);
-      case eLogicalSideIEnd:
+      case LogicalSide::IEnd:
         return IEnd(aWM);
     }
 
@@ -1298,13 +1308,13 @@ class LogicalMargin {
   }
   nscoord& Side(LogicalSide aSide, WritingMode aWM) {
     switch (aSide) {
-      case eLogicalSideBStart:
+      case LogicalSide::BStart:
         return BStart(aWM);
-      case eLogicalSideBEnd:
+      case LogicalSide::BEnd:
         return BEnd(aWM);
-      case eLogicalSideIStart:
+      case LogicalSide::IStart:
         return IStart(aWM);
-      case eLogicalSideIEnd:
+      case LogicalSide::IEnd:
         return IEnd(aWM);
     }
 
@@ -1646,13 +1656,13 @@ class LogicalRect {
   }
 
   nscoord Start(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? IStart(aWM) : BStart(aWM);
+    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
   }
   nscoord End(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? IEnd(aWM) : BEnd(aWM);
+    return aAxis == LogicalAxis::Inline ? IEnd(aWM) : BEnd(aWM);
   }
   nscoord Size(LogicalAxis aAxis, WritingMode aWM) const {
-    return aAxis == eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
+    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
   }
 
   /**
@@ -1680,10 +1690,10 @@ class LogicalRect {
     return mBSize;
   }
   nscoord& Start(LogicalAxis aAxis, WritingMode aWM) {
-    return aAxis == eLogicalAxisInline ? IStart(aWM) : BStart(aWM);
+    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
   }
   nscoord& Size(LogicalAxis aAxis, WritingMode aWM) {
-    return aAxis == eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
+    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
   }
 
   /**
@@ -2055,22 +2065,22 @@ const T& StyleRect<T>::Get(WritingMode aWM, LogicalSide aSide) const {
 
 template <typename T>
 const T& StyleRect<T>::GetIStart(WritingMode aWM) const {
-  return Get(aWM, eLogicalSideIStart);
+  return Get(aWM, LogicalSide::IStart);
 }
 
 template <typename T>
 const T& StyleRect<T>::GetBStart(WritingMode aWM) const {
-  return Get(aWM, eLogicalSideBStart);
+  return Get(aWM, LogicalSide::BStart);
 }
 
 template <typename T>
 const T& StyleRect<T>::GetIEnd(WritingMode aWM) const {
-  return Get(aWM, eLogicalSideIEnd);
+  return Get(aWM, LogicalSide::IEnd);
 }
 
 template <typename T>
 const T& StyleRect<T>::GetBEnd(WritingMode aWM) const {
-  return Get(aWM, eLogicalSideBEnd);
+  return Get(aWM, LogicalSide::BEnd);
 }
 
 template <typename T>
@@ -2080,38 +2090,38 @@ T& StyleRect<T>::Get(WritingMode aWM, LogicalSide aSide) {
 
 template <typename T>
 T& StyleRect<T>::GetIStart(WritingMode aWM) {
-  return Get(aWM, eLogicalSideIStart);
+  return Get(aWM, LogicalSide::IStart);
 }
 
 template <typename T>
 T& StyleRect<T>::GetBStart(WritingMode aWM) {
-  return Get(aWM, eLogicalSideBStart);
+  return Get(aWM, LogicalSide::BStart);
 }
 
 template <typename T>
 T& StyleRect<T>::GetIEnd(WritingMode aWM) {
-  return Get(aWM, eLogicalSideIEnd);
+  return Get(aWM, LogicalSide::IEnd);
 }
 
 template <typename T>
 T& StyleRect<T>::GetBEnd(WritingMode aWM) {
-  return Get(aWM, eLogicalSideBEnd);
+  return Get(aWM, LogicalSide::BEnd);
 }
 
 template <typename T>
 const T& StyleRect<T>::Start(mozilla::LogicalAxis aAxis,
                              mozilla::WritingMode aWM) const {
-  return Get(aWM, aAxis == mozilla::eLogicalAxisInline
-                      ? mozilla::eLogicalSideIStart
-                      : mozilla::eLogicalSideBStart);
+  return Get(aWM, aAxis == mozilla::LogicalAxis::Inline
+                      ? mozilla::LogicalSide::IStart
+                      : mozilla::LogicalSide::BStart);
 }
 
 template <typename T>
 const T& StyleRect<T>::End(mozilla::LogicalAxis aAxis,
                            mozilla::WritingMode aWM) const {
-  return Get(aWM, aAxis == mozilla::eLogicalAxisInline
-                      ? mozilla::eLogicalSideIEnd
-                      : mozilla::eLogicalSideBEnd);
+  return Get(aWM, aAxis == mozilla::LogicalAxis::Inline
+                      ? mozilla::LogicalSide::IEnd
+                      : mozilla::LogicalSide::BEnd);
 }
 
 inline AspectRatio AspectRatio::ConvertToWritingMode(
@@ -2147,15 +2157,15 @@ inline const mozilla::StyleMaxSize& nsStylePosition::MaxBSize(
 }
 inline const mozilla::StyleSize& nsStylePosition::Size(
     mozilla::LogicalAxis aAxis, WritingMode aWM) const {
-  return aAxis == mozilla::eLogicalAxisInline ? ISize(aWM) : BSize(aWM);
+  return aAxis == mozilla::LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
 }
 inline const mozilla::StyleSize& nsStylePosition::MinSize(
     mozilla::LogicalAxis aAxis, WritingMode aWM) const {
-  return aAxis == mozilla::eLogicalAxisInline ? MinISize(aWM) : MinBSize(aWM);
+  return aAxis == mozilla::LogicalAxis::Inline ? MinISize(aWM) : MinBSize(aWM);
 }
 inline const mozilla::StyleMaxSize& nsStylePosition::MaxSize(
     mozilla::LogicalAxis aAxis, WritingMode aWM) const {
-  return aAxis == mozilla::eLogicalAxisInline ? MaxISize(aWM) : MaxBSize(aWM);
+  return aAxis == mozilla::LogicalAxis::Inline ? MaxISize(aWM) : MaxBSize(aWM);
 }
 
 inline bool nsStylePosition::ISizeDependsOnContainer(WritingMode aWM) const {
@@ -2205,26 +2215,26 @@ inline bool nsStyleMargin::HasInlineAxisAuto(mozilla::WritingMode aWM) const {
 }
 inline bool nsStyleMargin::HasAuto(mozilla::LogicalAxis aAxis,
                                    mozilla::WritingMode aWM) const {
-  return aAxis == mozilla::eLogicalAxisInline ? HasInlineAxisAuto(aWM)
-                                              : HasBlockAxisAuto(aWM);
+  return aAxis == mozilla::LogicalAxis::Inline ? HasInlineAxisAuto(aWM)
+                                               : HasBlockAxisAuto(aWM);
 }
 
 inline mozilla::StyleAlignFlags nsStylePosition::UsedSelfAlignment(
     mozilla::LogicalAxis aAxis, const mozilla::ComputedStyle* aParent) const {
-  return aAxis == mozilla::eLogicalAxisBlock ? UsedAlignSelf(aParent)._0
-                                             : UsedJustifySelf(aParent)._0;
+  return aAxis == mozilla::LogicalAxis::Block ? UsedAlignSelf(aParent)._0
+                                              : UsedJustifySelf(aParent)._0;
 }
 
 inline mozilla::StyleContentDistribution nsStylePosition::UsedContentAlignment(
     mozilla::LogicalAxis aAxis) const {
-  return aAxis == mozilla::eLogicalAxisBlock ? mAlignContent : mJustifyContent;
+  return aAxis == mozilla::LogicalAxis::Block ? mAlignContent : mJustifyContent;
 }
 
 inline mozilla::StyleContentDistribution nsStylePosition::UsedTracksAlignment(
     mozilla::LogicalAxis aAxis, uint32_t aIndex) const {
   using T = mozilla::StyleAlignFlags;
   const auto& tracksAlignment =
-      aAxis == mozilla::eLogicalAxisBlock ? mAlignTracks : mJustifyTracks;
+      aAxis == mozilla::LogicalAxis::Block ? mAlignTracks : mJustifyTracks;
   if (MOZ_LIKELY(tracksAlignment.IsEmpty())) {
     // An empty array encodes the initial value, 'normal', which behaves as
     // 'start' for Grid containers.
diff --git a/layout/generic/crashtests/1410243-1.html b/layout/generic/crashtests/1410243-1.html
new file mode 100644
index 0000000000..42a005e85b
--- /dev/null
+++ b/layout/generic/crashtests/1410243-1.html
@@ -0,0 +1,26 @@
+<!-- //DDBEGIN -->
+<style>
+* { margin-bottom: -1em; font-size: xx-large; }
+.cl1 { Max-height: 93; column-width: 0; position: fixed; }
+</style>
+<script>
+function eventhandler1() {
+try { htmlvar0002.style.setProperty("display", "grid"); } catch(e) { }
+try { svgvar0001.clientWidth; } catch(e) { }
+try { htmlvar0002.style.setProperty("grid-template", "0px/0px"); } catch(e) { }
+}
+</script>
+<details class="cl1" open="" ontoggle="eventhandler1()">
+<summary id="svgvar0001"/></summary>
+<a>
+<ol id="htmlvar0002">
+<keygen>
+>
+A
+AA
+A
+A
+A
+A
+<a>
+<!-- //DDEND -->
diff --git a/layout/generic/crashtests/1741488-1.html b/layout/generic/crashtests/1741488-1.html
new file mode 100644
index 0000000000..74d7c49feb
--- /dev/null
+++ b/layout/generic/crashtests/1741488-1.html
@@ -0,0 +1,23 @@
+<html class="reftest-wait">
+<style>
+#b {
+  writing-mode: vertical-rl;
+  content: url(data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=);
+}
+</style>
+<script>
+let pp;
+document.addEventListener("MozReftestInvalidate", () => {
+  a.after("1")
+  a.insertAdjacentHTML("afterEnd", b.outerHTML);
+  pp = SpecialPowers.wrap(self).printPreview();
+  setTimeout(function() {
+    pp.close();
+    document.documentElement.className = "";
+  }, 400);
+})
+</script>
+<math>
+<munder>
+<mn id="a">2</mn>
+<dl id="b"></dl>
diff --git a/layout/generic/crashtests/1881375-1-helper.html b/layout/generic/crashtests/1881375-1-helper.html
new file mode 100644
index 0000000000..5c79e4981f
--- /dev/null
+++ b/layout/generic/crashtests/1881375-1-helper.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<script>
+// Notify our parent and reload ourselves.
+function notifyAndReload() {
+  if (window.parent) {
+    window.parent.postMessage("reloaded", "*");
+  }
+  window.location.reload(true)
+}
+</script>
+<style>
+*:nth-child(even) {
+  height: 16em;
+  list-style-image: url(data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=);
+}
+#a {
+  display: inline-grid;
+  grid-auto-flow: column dense;
+}
+#b {
+  padding-top: 8192vmax;
+}
+* {
+  align-content: center;
+  column-width: 1em;
+  float: inline-end;
+}
+</style>
+<body onload="setTimeout(notifyAndReload, 0)">
+<picture></picture>
+<iframe></iframe>
+<isindex>
+<svg></svg>
+<samp id="a">
+<q>
+<a id="b">
+</q>
+<li>
diff --git a/layout/generic/crashtests/1881375-1.html b/layout/generic/crashtests/1881375-1.html
new file mode 100644
index 0000000000..8cef260433
--- /dev/null
+++ b/layout/generic/crashtests/1881375-1.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<script>
+// Loop count for the handler below. This value seems to be enough for the
+// crashtest to be likely to trigger the crash.
+const MAX_LOADS = 3;
+let loadCount = 0;
+
+// Handler which gets invoked by the iframe whenever it completes a load
+// (and dynamically reloads itself). This lets us allow the testcase to
+// reload over and over (as seems to be required to trigger the crash),
+// while also keeping the test duration reasonably bounded.
+window.addEventListener(
+  "message",
+  (event) => {
+    if (loadCount++ == MAX_LOADS) {
+      // After MAX_LOADS reloads of the iframe, call ourselves done.
+      myIframe.remove();
+      document.documentElement.className = "";
+    }
+  }
+);
+
+</script>
+<iframe id="myIframe" src="1881375-1-helper.html"></iframe>
diff --git a/layout/generic/crashtests/481921.ogg b/layout/generic/crashtests/481921.ogg
deleted file mode 100644
index 0c41c3cd6b..0000000000
--- a/layout/generic/crashtests/481921.ogg
+++ /dev/null
diff --git a/layout/generic/crashtests/crashtests.list b/layout/generic/crashtests/crashtests.list
index 1c184739d7..2aea090a6f 100644
--- a/layout/generic/crashtests/crashtests.list
+++ b/layout/generic/crashtests/crashtests.list
@@ -678,6 +678,7 @@ load 1405443.html
 load 1405813.html
 load 1405896.html
 load 1406252-1.html
+asserts(2) load 1410243-1.html # assertion is bug 574889
 load 1415185.html
 load 1416544.html
 load 1427824.html
@@ -804,6 +805,7 @@ load 1728319.html
 asserts(2-8) load 1730506.html # asserts from integer overflow & bogus sizes
 asserts(1-4) load 1730570.html # asserts from integer overflow & bogus sizes
 load 1734015.html
+skip-if(Android) load 1741488-1.html # printPreview doesn't work on android
 load 1776079.html
 asserts(0-2) load 1791606.html
 load 1799749.html
@@ -812,3 +814,4 @@ load 1816574.html
 load 1821603.html
 load 1822118.html
 load 1825434.html
+asserts(0-85) load 1881375-1.html # bug 1890687 - assertions about fragmentation invariants, failing many times because the test runs in a loop
diff --git a/layout/generic/nsAbsoluteContainingBlock.cpp b/layout/generic/nsAbsoluteContainingBlock.cpp
index 3cfe7b5b2d..4f561688bf 100644
--- a/layout/generic/nsAbsoluteContainingBlock.cpp
+++ b/layout/generic/nsAbsoluteContainingBlock.cpp
@@ -522,7 +522,7 @@ static nscoord OffsetToAlignedStaticPos(const ReflowInput& aKidReflowInput,
     return 0;  // (leave the child at the start of its alignment container)
   }
 
-  nscoord alignAreaSizeInAxis = (pcAxis == eLogicalAxisInline)
+  nscoord alignAreaSizeInAxis = (pcAxis == LogicalAxis::Inline)
                                     ? alignAreaSize.ISize(pcWM)
                                     : alignAreaSize.BSize(pcWM);
 
@@ -619,7 +619,7 @@ void nsAbsoluteContainingBlock::ResolveSizeDependentOffsets(
       placeholderContainer = GetPlaceholderContainer(aKidReflowInput.mFrame);
       nscoord offset = OffsetToAlignedStaticPos(
           aKidReflowInput, aKidSize, logicalCBSizeOuterWM, placeholderContainer,
-          outerWM, eLogicalAxisInline);
+          outerWM, LogicalAxis::Inline);
       // Shift IStart from its current position (at start corner of the
       // alignment container) by the returned offset.  And set IEnd to the
       // distance between the kid's end edge to containing block's end edge.
@@ -639,7 +639,7 @@ void nsAbsoluteContainingBlock::ResolveSizeDependentOffsets(
       }
       nscoord offset = OffsetToAlignedStaticPos(
           aKidReflowInput, aKidSize, logicalCBSizeOuterWM, placeholderContainer,
-          outerWM, eLogicalAxisBlock);
+          outerWM, LogicalAxis::Block);
       // Shift BStart from its current position (at start corner of the
       // alignment container) by the returned offset.  And set BEnd to the
       // distance between the kid's end edge to containing block's end edge.
diff --git a/layout/generic/nsBackdropFrame.cpp b/layout/generic/nsBackdropFrame.cpp
index 20d3fcd368..178caa3e0c 100644
--- a/layout/generic/nsBackdropFrame.cpp
+++ b/layout/generic/nsBackdropFrame.cpp
@@ -70,7 +70,6 @@ void nsBackdropFrame::Reflow(nsPresContext* aPresContext,
                              nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsBackdropFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Note that this frame is a child of the viewport frame.
diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index a25e4e996e..4582c29e0b 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -813,8 +813,6 @@ nscoord nsBlockFrame::GetMinISize(gfxContext* aRenderingContext) {
     return firstInFlow->GetMinISize(aRenderingContext);
   }
 
-  DISPLAY_MIN_INLINE_SIZE(this, mCachedMinISize);
-
   CheckIntrinsicCacheAgainstShrinkWrapState();
 
   if (mCachedMinISize != NS_INTRINSIC_ISIZE_UNKNOWN) {
@@ -902,8 +900,6 @@ nscoord nsBlockFrame::GetPrefISize(gfxContext* aRenderingContext) {
     return firstInFlow->GetPrefISize(aRenderingContext);
   }
 
-  DISPLAY_PREF_INLINE_SIZE(this, mCachedPrefISize);
-
   CheckIntrinsicCacheAgainstShrinkWrapState();
 
   if (mCachedPrefISize != NS_INTRINSIC_ISIZE_UNKNOWN) {
@@ -1348,7 +1344,6 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
 
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsBlockFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
 #ifdef DEBUG
@@ -1453,14 +1448,18 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
   // maintain when doing text-wrap: balance.
   struct BalanceTarget {
     // If line-clamp is in effect, mContent and mOffset indicate the starting
-    // position of the first line after the clamp limit. If line-clamp is not
-    // in use, mContent is null and mOffset is the total number of lines that
-    // the block must contain.
+    // position of the first line after the clamp limit, and mBlockCoord is the
+    // block-axis offset of its position.
+    // If line-clamp is not in use, mContent is null, mOffset is the total
+    // number of lines that the block must contain, and mBlockCoord is its end
+    // edge in the block direction.
     nsIContent* mContent = nullptr;
     int32_t mOffset = -1;
+    nscoord mBlockCoord = 0;
 
     bool operator==(const BalanceTarget& aOther) const {
-      return mContent == aOther.mContent && mOffset == aOther.mOffset;
+      return mContent == aOther.mContent && mOffset == aOther.mOffset &&
+             mBlockCoord == aOther.mBlockCoord;
     }
     bool operator!=(const BalanceTarget& aOther) const {
       return !(*this == aOther);
@@ -1506,7 +1505,7 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
       auto* textFrame = static_cast<nsTextFrame*>(firstChild);
       offset = textFrame->GetContentOffset();
     }
-    return BalanceTarget{content, offset};
+    return BalanceTarget{content, offset, iter.get()->BStart()};
   };
 
   // "balancing" is implemented by shortening the effective inline-size of the
@@ -1545,6 +1544,7 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
         // no balancing is needed; just break from the balance loop.
         break;
       }
+      balanceTarget.mBlockCoord = mLines.back()->BEnd();
       // Initialize the amount of inset to try, and the iteration step size.
       balanceStep = aReflowInput.ComputedISize() / balanceTarget.mOffset;
       trialState.ResetForBalance(balanceStep);
@@ -1581,7 +1581,8 @@ void nsBlockFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
       }
       int32_t numLines =
           countLinesUpTo(StaticPrefs::layout_css_text_wrap_balance_limit());
-      return numLines == balanceTarget.mOffset;
+      return numLines == balanceTarget.mOffset &&
+             mLines.back()->BEnd() == balanceTarget.mBlockCoord;
     };
 
     // If we're in the process of a balance operation, check whether we've
@@ -2817,7 +2818,7 @@ void nsBlockFrame::PropagateFloatDamage(BlockReflowState& aState,
 
 static bool LineHasClear(nsLineBox* aLine) {
   return aLine->IsBlock()
-             ? (aLine->HasForcedLineBreakBefore() ||
+             ? (aLine->HasFloatClearTypeBefore() ||
                 aLine->mFirstChild->HasAnyStateBits(
                     NS_BLOCK_HAS_CLEAR_CHILDREN) ||
                 !nsBlockFrame::BlockCanIntersectFloats(aLine->mFirstChild))
@@ -2984,7 +2985,7 @@ bool nsBlockFrame::ReflowDirtyLines(BlockReflowState& aState) {
     // We have to reflow the line if it's a block whose clearance
     // might have changed, so detect that.
     if (!line->IsDirty() &&
-        (line->HasForcedLineBreakBefore() || floatAvoidingBlock)) {
+        (line->HasFloatClearTypeBefore() || floatAvoidingBlock)) {
       nscoord curBCoord = aState.mBCoord;
       // See where we would be after applying any clearance due to
       // BRs.
@@ -3934,9 +3935,9 @@ bool nsBlockFrame::IsSelfEmpty() {
   const nsStyleBorder* border = StyleBorder();
   const nsStylePadding* padding = StylePadding();
 
-  if (border->GetComputedBorderWidth(wm.PhysicalSide(eLogicalSideBStart)) !=
+  if (border->GetComputedBorderWidth(wm.PhysicalSide(LogicalSide::BStart)) !=
           0 ||
-      border->GetComputedBorderWidth(wm.PhysicalSide(eLogicalSideBEnd)) != 0 ||
+      border->GetComputedBorderWidth(wm.PhysicalSide(LogicalSide::BEnd)) != 0 ||
       !nsLayoutUtils::IsPaddingZero(padding->mPadding.GetBStart(wm)) ||
       !nsLayoutUtils::IsPaddingZero(padding->mPadding.GetBEnd(wm))) {
     return false;
@@ -4051,7 +4052,7 @@ void nsBlockFrame::ReflowBlockFrame(BlockReflowState& aState,
   // Clear past floats before the block if the clear style is not none
   aLine->ClearForcedLineBreak();
   if (clearType != StyleClear::None) {
-    aLine->SetForcedLineBreakBefore(clearType);
+    aLine->SetFloatClearTypeBefore(clearType);
   }
 
   // See if we should apply the block-start margin. If the block frame being
diff --git a/layout/generic/nsCanvasFrame.cpp b/layout/generic/nsCanvasFrame.cpp
index 64c56b1c00..b4b108905f 100644
--- a/layout/generic/nsCanvasFrame.cpp
+++ b/layout/generic/nsCanvasFrame.cpp
@@ -606,24 +606,16 @@ void nsCanvasFrame::PaintFocus(DrawTarget* aDrawTarget, nsPoint aPt) {
 
 /* virtual */
 nscoord nsCanvasFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  if (mFrames.IsEmpty())
-    result = 0;
-  else
-    result = mFrames.FirstChild()->GetMinISize(aRenderingContext);
-  return result;
+  return mFrames.IsEmpty()
+             ? 0
+             : mFrames.FirstChild()->GetMinISize(aRenderingContext);
 }
 
 /* virtual */
 nscoord nsCanvasFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  if (mFrames.IsEmpty())
-    result = 0;
-  else
-    result = mFrames.FirstChild()->GetPrefISize(aRenderingContext);
-  return result;
+  return mFrames.IsEmpty()
+             ? 0
+             : mFrames.FirstChild()->GetPrefISize(aRenderingContext);
 }
 
 void nsCanvasFrame::Reflow(nsPresContext* aPresContext,
@@ -632,7 +624,6 @@ void nsCanvasFrame::Reflow(nsPresContext* aPresContext,
                            nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsCanvasFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE_REFLOW_IN("nsCanvasFrame::Reflow");
 
diff --git a/layout/generic/nsColumnSetFrame.cpp b/layout/generic/nsColumnSetFrame.cpp
index cd97519a98..a9d3e28138 100644
--- a/layout/generic/nsColumnSetFrame.cpp
+++ b/layout/generic/nsColumnSetFrame.cpp
@@ -408,7 +408,6 @@ static void MoveChildTo(nsIFrame* aChild, LogicalPoint aOrigin, WritingMode aWM,
 
 nscoord nsColumnSetFrame::GetMinISize(gfxContext* aRenderingContext) {
   nscoord iSize = 0;
-  DISPLAY_MIN_INLINE_SIZE(this, iSize);
 
   if (mFrames.FirstChild()) {
     // We want to ignore this in the case that we're size contained
@@ -443,8 +442,6 @@ nscoord nsColumnSetFrame::GetPrefISize(gfxContext* aRenderingContext) {
   // the child's preferred width, times the number of columns, plus the width
   // of any required column gaps
   // XXX what about forced column breaks here?
-  nscoord result = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
   const nsStyleColumn* colStyle = StyleColumn();
 
   nscoord colISize;
@@ -466,8 +463,7 @@ nscoord nsColumnSetFrame::GetPrefISize(gfxContext* aRenderingContext) {
           ? 1
           : colStyle->mColumnCount;
   nscoord colGap = ColumnUtils::GetColumnGap(this, NS_UNCONSTRAINEDSIZE);
-  result = ColumnUtils::IntrinsicISize(numColumns, colGap, colISize);
-  return result;
+  return ColumnUtils::IntrinsicISize(numColumns, colGap, colISize);
 }
 
 nsColumnSetFrame::ColumnBalanceData nsColumnSetFrame::ReflowColumns(
@@ -1202,7 +1198,6 @@ void nsColumnSetFrame::Reflow(nsPresContext* aPresContext,
   nsPresContext::InterruptPreventer noInterrupts(aPresContext);
 
   DO_GLOBAL_REFLOW_COUNT("nsColumnSetFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   MOZ_ASSERT(aReflowInput.mCBReflowInput->mFrame->StyleColumn()
diff --git a/layout/generic/nsContainerFrame.cpp b/layout/generic/nsContainerFrame.cpp
index 2577a7a00d..2c9e707830 100644
--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -814,8 +814,7 @@ LogicalSize nsContainerFrame::ComputeAutoSize(
   LogicalSize result(aWM, 0xdeadbeef, NS_UNCONSTRAINEDSIZE);
   nscoord availBased =
       aAvailableISize - aMargin.ISize(aWM) - aBorderPadding.ISize(aWM);
-  // replaced elements always shrink-wrap
-  if (aFlags.contains(ComputeSizeFlag::ShrinkWrap) || IsReplaced()) {
+  if (aFlags.contains(ComputeSizeFlag::ShrinkWrap)) {
     // Only bother computing our 'auto' ISize if the result will be used.
     const auto& styleISize = aSizeOverrides.mStyleISize
                                  ? *aSizeOverrides.mStyleISize
@@ -2201,9 +2200,9 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
   // This variable only gets meaningfully set if isFlexItem is true.  It
   // indicates which axis (in this frame's own WM) corresponds to its
   // flex container's main axis.
-  LogicalAxis flexMainAxis = eLogicalAxisBlock;
+  LogicalAxis flexMainAxis = LogicalAxis::Block;
   if (isFlexItem && nsFlexContainerFrame::IsItemInlineAxisMainAxis(this)) {
-    flexMainAxis = eLogicalAxisInline;
+    flexMainAxis = LogicalAxis::Inline;
   }
 
   // Handle intrinsic sizes and their interaction with
@@ -2263,8 +2262,8 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
                               aSizeOverrides, aFlags)
                 .mISize;
   } else if (MOZ_UNLIKELY(isGridItem) &&
-             !parentFrame->IsMasonry(isOrthogonal ? eLogicalAxisBlock
-                                                  : eLogicalAxisInline)) {
+             !parentFrame->IsMasonry(isOrthogonal ? LogicalAxis::Block
+                                                  : LogicalAxis::Inline)) {
     MOZ_ASSERT(!IsTrueOverflowContainer());
     // 'auto' inline-size for grid-level box - apply 'stretch' as needed:
     auto cbSize = aCBSize.ISize(aWM);
@@ -2291,7 +2290,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
   const auto& maxISizeCoord = stylePos->MaxISize(aWM);
 
   if (!maxISizeCoord.IsNone() &&
-      !(isFlexItem && flexMainAxis == eLogicalAxisInline)) {
+      !(isFlexItem && flexMainAxis == LogicalAxis::Inline)) {
     maxISize = ComputeISizeValue(aRenderingContext, aWM, aCBSize,
                                  boxSizingAdjust, boxSizingToMarginEdgeISize,
                                  maxISizeCoord, aSizeOverrides, aFlags)
@@ -2307,7 +2306,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
   const auto& minISizeCoord = stylePos->MinISize(aWM);
 
   if (!minISizeCoord.IsAuto() &&
-      !(isFlexItem && flexMainAxis == eLogicalAxisInline)) {
+      !(isFlexItem && flexMainAxis == LogicalAxis::Inline)) {
     minISize = ComputeISizeValue(aRenderingContext, aWM, aCBSize,
                                  boxSizingAdjust, boxSizingToMarginEdgeISize,
                                  minISizeCoord, aSizeOverrides, aFlags)
@@ -2326,8 +2325,8 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
                                              boxSizingAdjust.BSize(aWM),
                                              styleBSize.AsLengthPercentage());
   } else if (MOZ_UNLIKELY(isGridItem) &&
-             !parentFrame->IsMasonry(isOrthogonal ? eLogicalAxisInline
-                                                  : eLogicalAxisBlock)) {
+             !parentFrame->IsMasonry(isOrthogonal ? LogicalAxis::Inline
+                                                  : LogicalAxis::Block)) {
     MOZ_ASSERT(!IsTrueOverflowContainer());
     // 'auto' block-size for grid-level box - apply 'stretch' as needed:
     auto cbSize = aCBSize.BSize(aWM);
@@ -2354,7 +2353,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
   const auto& maxBSizeCoord = stylePos->MaxBSize(aWM);
 
   if (!nsLayoutUtils::IsAutoBSize(maxBSizeCoord, aCBSize.BSize(aWM)) &&
-      !(isFlexItem && flexMainAxis == eLogicalAxisBlock)) {
+      !(isFlexItem && flexMainAxis == LogicalAxis::Block)) {
     maxBSize = nsLayoutUtils::ComputeBSizeValue(
         aCBSize.BSize(aWM), boxSizingAdjust.BSize(aWM),
         maxBSizeCoord.AsLengthPercentage());
@@ -2365,7 +2364,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
   const auto& minBSizeCoord = stylePos->MinBSize(aWM);
 
   if (!nsLayoutUtils::IsAutoBSize(minBSizeCoord, aCBSize.BSize(aWM)) &&
-      !(isFlexItem && flexMainAxis == eLogicalAxisBlock)) {
+      !(isFlexItem && flexMainAxis == LogicalAxis::Block)) {
     minBSize = nsLayoutUtils::ComputeBSizeValue(
         aCBSize.BSize(aWM), boxSizingAdjust.BSize(aWM),
         minBSizeCoord.AsLengthPercentage());
@@ -2389,8 +2388,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
         tentISize = intrinsicISize;
       } else if (hasIntrinsicBSize && aspectRatio) {
         tentISize = aspectRatio.ComputeRatioDependentSize(
-            LogicalAxis::eLogicalAxisInline, aWM, intrinsicBSize,
-            boxSizingAdjust);
+            LogicalAxis::Inline, aWM, intrinsicBSize, boxSizingAdjust);
       } else if (aspectRatio) {
         tentISize =
             aCBSize.ISize(aWM) - boxSizingToMarginEdgeISize;  // XXX scrollbar?
@@ -2413,7 +2411,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
         tentBSize = intrinsicBSize;
       } else if (aspectRatio) {
         tentBSize = aspectRatio.ComputeRatioDependentSize(
-            LogicalAxis::eLogicalAxisBlock, aWM, tentISize, boxSizingAdjust);
+            LogicalAxis::Block, aWM, tentISize, boxSizingAdjust);
       } else {
         tentBSize = fallbackIntrinsicSize.BSize(aWM);
       }
@@ -2431,29 +2429,29 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
         } else if (stretchB == eStretchPreservingRatio && aspectRatio) {
           // 'normal' / 'stretch'
           tentBSize = aspectRatio.ComputeRatioDependentSize(
-              LogicalAxis::eLogicalAxisBlock, aWM, iSize, boxSizingAdjust);
+              LogicalAxis::Block, aWM, iSize, boxSizingAdjust);
         }
       } else if (stretchB == eStretch) {
         tentBSize = bSize;  // 'stretch' / * (except 'stretch')
         if (stretchI == eStretchPreservingRatio && aspectRatio) {
           // 'stretch' / 'normal'
           tentISize = aspectRatio.ComputeRatioDependentSize(
-              LogicalAxis::eLogicalAxisInline, aWM, bSize, boxSizingAdjust);
+              LogicalAxis::Inline, aWM, bSize, boxSizingAdjust);
         }
       } else if (stretchI == eStretchPreservingRatio && aspectRatio) {
         tentISize = iSize;  // * (except 'stretch') / 'normal'
         tentBSize = aspectRatio.ComputeRatioDependentSize(
-            LogicalAxis::eLogicalAxisBlock, aWM, iSize, boxSizingAdjust);
+            LogicalAxis::Block, aWM, iSize, boxSizingAdjust);
         if (stretchB == eStretchPreservingRatio && tentBSize > bSize) {
           // Stretch within the CB size with preserved intrinsic ratio.
           tentBSize = bSize;  // 'normal' / 'normal'
           tentISize = aspectRatio.ComputeRatioDependentSize(
-              LogicalAxis::eLogicalAxisInline, aWM, bSize, boxSizingAdjust);
+              LogicalAxis::Inline, aWM, bSize, boxSizingAdjust);
         }
       } else if (stretchB == eStretchPreservingRatio && aspectRatio) {
         tentBSize = bSize;  // 'normal' / * (except 'normal' and 'stretch')
         tentISize = aspectRatio.ComputeRatioDependentSize(
-            LogicalAxis::eLogicalAxisInline, aWM, bSize, boxSizingAdjust);
+            LogicalAxis::Inline, aWM, bSize, boxSizingAdjust);
       }
 
       // ComputeAutoSizeWithIntrinsicDimensions preserves the ratio when
@@ -2480,7 +2478,7 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
       if (stretchI != eStretch) {
         if (aspectRatio) {
           iSize = aspectRatio.ComputeRatioDependentSize(
-              LogicalAxis::eLogicalAxisInline, aWM, bSize, boxSizingAdjust);
+              LogicalAxis::Inline, aWM, bSize, boxSizingAdjust);
         } else if (hasIntrinsicISize) {
           if (!(aFlags.contains(ComputeSizeFlag::IClampMarginBoxMinSize) &&
                 intrinsicISize > iSize)) {
@@ -2498,8 +2496,8 @@ LogicalSize nsContainerFrame::ComputeSizeWithIntrinsicDimensions(
       iSize = NS_CSS_MINMAX(iSize, minISize, maxISize);
       if (stretchB != eStretch) {
         if (aspectRatio) {
-          bSize = aspectRatio.ComputeRatioDependentSize(
-              LogicalAxis::eLogicalAxisBlock, aWM, iSize, boxSizingAdjust);
+          bSize = aspectRatio.ComputeRatioDependentSize(LogicalAxis::Block, aWM,
+                                                        iSize, boxSizingAdjust);
         } else if (hasIntrinsicBSize) {
           if (!(aFlags.contains(ComputeSizeFlag::BClampMarginBoxMinSize) &&
                 intrinsicBSize > bSize)) {
diff --git a/layout/generic/nsContainerFrame.h b/layout/generic/nsContainerFrame.h
index 09f6cf76f5..cb0a09db20 100644
--- a/layout/generic/nsContainerFrame.h
+++ b/layout/generic/nsContainerFrame.h
@@ -1076,126 +1076,4 @@ class nsOverflowContinuationTracker {
   bool mWalkOOFFrames;
 };
 
-// Start Display Reflow Debugging
-#ifdef DEBUG
-
-struct DR_cookie {
-  DR_cookie(nsPresContext* aPresContext, nsIFrame* aFrame,
-            const mozilla::ReflowInput& aReflowInput,
-            mozilla::ReflowOutput& aMetrics, nsReflowStatus& aStatus);
-  ~DR_cookie();
-  void Change() const;
-
-  nsPresContext* mPresContext;
-  nsIFrame* mFrame;
-  const mozilla::ReflowInput& mReflowInput;
-  mozilla::ReflowOutput& mMetrics;
-  nsReflowStatus& mStatus;
-  void* mValue;
-};
-
-struct DR_layout_cookie {
-  explicit DR_layout_cookie(nsIFrame* aFrame);
-  ~DR_layout_cookie();
-
-  nsIFrame* mFrame;
-  void* mValue;
-};
-
-struct DR_intrinsic_inline_size_cookie {
-  DR_intrinsic_inline_size_cookie(nsIFrame* aFrame, const char* aType,
-                                  nscoord& aResult);
-  ~DR_intrinsic_inline_size_cookie();
-
-  nsIFrame* mFrame;
-  const char* mType;
-  nscoord& mResult;
-  void* mValue;
-};
-
-struct DR_intrinsic_size_cookie {
-  DR_intrinsic_size_cookie(nsIFrame* aFrame, const char* aType,
-                           nsSize& aResult);
-  ~DR_intrinsic_size_cookie();
-
-  nsIFrame* mFrame;
-  const char* mType;
-  nsSize& mResult;
-  void* mValue;
-};
-
-struct DR_init_constraints_cookie {
-  DR_init_constraints_cookie(
-      nsIFrame* aFrame, mozilla::ReflowInput* aState, nscoord aCBWidth,
-      nscoord aCBHeight, const mozilla::Maybe<mozilla::LogicalMargin> aBorder,
-      const mozilla::Maybe<mozilla::LogicalMargin> aPadding);
-  ~DR_init_constraints_cookie();
-
-  nsIFrame* mFrame;
-  mozilla::ReflowInput* mState;
-  void* mValue;
-};
-
-struct DR_init_offsets_cookie {
-  DR_init_offsets_cookie(nsIFrame* aFrame,
-                         mozilla::SizeComputationInput* aState,
-                         nscoord aPercentBasis,
-                         mozilla::WritingMode aCBWritingMode,
-                         const mozilla::Maybe<mozilla::LogicalMargin> aBorder,
-                         const mozilla::Maybe<mozilla::LogicalMargin> aPadding);
-  ~DR_init_offsets_cookie();
-
-  nsIFrame* mFrame;
-  mozilla::SizeComputationInput* mState;
-  void* mValue;
-};
-
-#  define DISPLAY_REFLOW(dr_pres_context, dr_frame, dr_rf_state,               \
-                         dr_rf_metrics, dr_rf_status)                          \
-    DR_cookie dr_cookie(dr_pres_context, dr_frame, dr_rf_state, dr_rf_metrics, \
-                        dr_rf_status);
-#  define DISPLAY_REFLOW_CHANGE() dr_cookie.Change();
-#  define DISPLAY_LAYOUT(dr_frame) DR_layout_cookie dr_cookie(dr_frame);
-#  define DISPLAY_MIN_INLINE_SIZE(dr_frame, dr_result) \
-    DR_intrinsic_inline_size_cookie dr_cookie(dr_frame, "Min", dr_result)
-#  define DISPLAY_PREF_INLINE_SIZE(dr_frame, dr_result) \
-    DR_intrinsic_inline_size_cookie dr_cookie(dr_frame, "Pref", dr_result)
-#  define DISPLAY_PREF_SIZE(dr_frame, dr_result) \
-    DR_intrinsic_size_cookie dr_cookie(dr_frame, "Pref", dr_result)
-#  define DISPLAY_MIN_SIZE(dr_frame, dr_result) \
-    DR_intrinsic_size_cookie dr_cookie(dr_frame, "Min", dr_result)
-#  define DISPLAY_MAX_SIZE(dr_frame, dr_result) \
-    DR_intrinsic_size_cookie dr_cookie(dr_frame, "Max", dr_result)
-#  define DISPLAY_INIT_CONSTRAINTS(dr_frame, dr_state, dr_cbw, dr_cbh, dr_bdr, \
-                                   dr_pad)                                     \
-    DR_init_constraints_cookie dr_cookie(dr_frame, dr_state, dr_cbw, dr_cbh,   \
-                                         dr_bdr, dr_pad)
-#  define DISPLAY_INIT_OFFSETS(dr_frame, dr_state, dr_pb, dr_cbwm, dr_bdr, \
-                               dr_pad)                                     \
-    DR_init_offsets_cookie dr_cookie(dr_frame, dr_state, dr_pb, dr_cbwm,   \
-                                     dr_bdr, dr_pad)
-
-#else
-
-#  define DISPLAY_REFLOW(dr_pres_context, dr_frame, dr_rf_state, \
-                         dr_rf_metrics, dr_rf_status)
-#  define DISPLAY_REFLOW_CHANGE()
-#  define DISPLAY_LAYOUT(dr_frame) PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_MIN_INLINE_SIZE(dr_frame, dr_result) \
-    PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_PREF_INLINE_SIZE(dr_frame, dr_result) \
-    PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_PREF_SIZE(dr_frame, dr_result) PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_MIN_SIZE(dr_frame, dr_result) PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_MAX_SIZE(dr_frame, dr_result) PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_INIT_CONSTRAINTS(dr_frame, dr_state, dr_cbw, dr_cbh, dr_bdr, \
-                                   dr_pad)                                     \
-    PR_BEGIN_MACRO PR_END_MACRO
-#  define DISPLAY_INIT_OFFSETS(dr_frame, dr_state, dr_pb, dr_cbwm, dr_bdr, \
-                               dr_pad)                                     \
-    PR_BEGIN_MACRO PR_END_MACRO
-
-#endif
-// End Display Reflow Debugging
-
 #endif /* nsContainerFrame_h___ */
diff --git a/layout/generic/nsFirstLetterFrame.cpp b/layout/generic/nsFirstLetterFrame.cpp
index fe294652c7..28d1b08a30 100644
--- a/layout/generic/nsFirstLetterFrame.cpp
+++ b/layout/generic/nsFirstLetterFrame.cpp
@@ -197,7 +197,6 @@ void nsFirstLetterFrame::Reflow(nsPresContext* aPresContext,
                                 nsReflowStatus& aReflowStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsFirstLetterFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aReflowStatus);
   MOZ_ASSERT(aReflowStatus.IsEmpty(),
              "Caller should pass a fresh reflow status!");
 
diff --git a/layout/generic/nsFlexContainerFrame.cpp b/layout/generic/nsFlexContainerFrame.cpp
index e5a719fee2..66f1e79609 100644
--- a/layout/generic/nsFlexContainerFrame.cpp
+++ b/layout/generic/nsFlexContainerFrame.cpp
@@ -14,14 +14,12 @@
 #include "mozilla/Baseline.h"
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/CSSOrderAwareFrameIterator.h"
-#include "mozilla/FloatingPoint.h"
 #include "mozilla/Logging.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/StaticPrefs_layout.h"
 #include "mozilla/WritingModes.h"
 #include "nsBlockFrame.h"
 #include "nsContentUtils.h"
-#include "nsCSSAnonBoxes.h"
 #include "nsDebug.h"
 #include "nsDisplayList.h"
 #include "nsFieldSetFrame.h"
@@ -43,10 +41,25 @@ using CachedBAxisMeasurement = nsFlexContainerFrame::CachedBAxisMeasurement;
 using CachedFlexItemData = nsFlexContainerFrame::CachedFlexItemData;
 
 static mozilla::LazyLogModule gFlexContainerLog("FlexContainer");
-#define FLEX_LOG(...) \
-  MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (__VA_ARGS__));
-#define FLEX_LOGV(...) \
-  MOZ_LOG(gFlexContainerLog, LogLevel::Verbose, (__VA_ARGS__));
+
+// FLEX_LOG is a top-level general log print.
+#define FLEX_LOG(message, ...) \
+  MOZ_LOG(gFlexContainerLog, LogLevel::Debug, (message, ##__VA_ARGS__));
+
+// FLEX_ITEM_LOG is a top-level log print for flex item.
+#define FLEX_ITEM_LOG(item_frame, message, ...) \
+  MOZ_LOG(gFlexContainerLog, LogLevel::Debug,   \
+          ("Flex item %p: " message, item_frame, ##__VA_ARGS__));
+
+// FLEX_LOGV is a verbose log print with built-in two spaces indentation. The
+// convention to use FLEX_LOGV is that FLEX_LOGV statements should generally be
+// preceded by one FLEX_LOG or FLEX_ITEM_LOG so that there's no need to repeat
+// information presented in the preceding LOG statement. If you want extra level
+// of indentation, just add two extra spaces at the start of the message string.
+#define FLEX_LOGV(message, ...) \
+  MOZ_LOG(gFlexContainerLog, LogLevel::Verbose, ("  " message, ##__VA_ARGS__));
+
+static const char* BoolToYesNo(bool aArg) { return aArg ? "yes" : "no"; }
 
 // Returns true if aFlexContainer is a frame for some element that has
 // display:-webkit-{inline-}box (or -moz-{inline-}box). aFlexContainer is
@@ -143,10 +156,10 @@ class MOZ_STACK_CLASS nsFlexContainerFrame::FlexboxAxisTracker {
 
   // Accessors:
   LogicalAxis MainAxis() const {
-    return IsRowOriented() ? eLogicalAxisInline : eLogicalAxisBlock;
+    return IsRowOriented() ? LogicalAxis::Inline : LogicalAxis::Block;
   }
   LogicalAxis CrossAxis() const {
-    return IsRowOriented() ? eLogicalAxisBlock : eLogicalAxisInline;
+    return IsRowOriented() ? LogicalAxis::Block : LogicalAxis::Inline;
   }
 
   LogicalSide MainAxisStartSide() const;
@@ -308,7 +321,7 @@ class MOZ_STACK_CLASS nsFlexContainerFrame::FlexboxAxisTracker {
                                                 : StyleAlignFlags::END;
     }
 
-    MOZ_ASSERT(MainAxis() == eLogicalAxisInline,
+    MOZ_ASSERT(MainAxis() == LogicalAxis::Inline,
                "Row-oriented flex container's main axis should be parallel to "
                "line-left <-> line-right axis!");
 
@@ -682,9 +695,8 @@ class nsFlexContainerFrame::FlexItem final {
     // to the [min,max] range:
     mMainSize = NS_CSS_MINMAX(mFlexBaseSize, mMainMinSize, mMainMaxSize);
 
-    FLEX_LOGV(
-        "Set flex base size: %d, hypothetical main size: %d for flex item %p",
-        mFlexBaseSize, mMainSize, mFrame);
+    FLEX_ITEM_LOG(mFrame, "Set flex base size: %d, hypothetical main size: %d",
+                  mFlexBaseSize, mMainSize);
   }
 
   // Setters used while we're resolving flexible lengths
@@ -1305,7 +1317,7 @@ StyleAlignFlags nsFlexContainerFrame::CSSAlignmentForAbsPosChild(
   // block axis), then the caller is really asking about our *main* axis.
   // Otherwise, the caller is asking about our cross axis.
   const bool isMainAxis =
-      (axisTracker.IsRowOriented() == (aLogicalAxis == eLogicalAxisInline));
+      (axisTracker.IsRowOriented() == (aLogicalAxis == LogicalAxis::Inline));
   const nsStylePosition* containerStylePos = StylePosition();
   const bool isAxisReversed = isMainAxis ? axisTracker.IsMainAxisReversed()
                                          : axisTracker.IsCrossAxisReversed();
@@ -1592,7 +1604,7 @@ static nscoord PartiallyResolveAutoMinSize(
   if (specifiedSizeSuggestion != nscoord_MAX) {
     // We have the specified size suggestion. Return it now since we don't need
     // to consider transferred size suggestion.
-    FLEX_LOGV(" Specified size suggestion: %d", specifiedSizeSuggestion);
+    FLEX_LOGV("Specified size suggestion: %d", specifiedSizeSuggestion);
     return specifiedSizeSuggestion;
   }
 
@@ -1611,7 +1623,7 @@ static nscoord PartiallyResolveAutoMinSize(
     transferredSizeSuggestion = aFlexItem.ClampMainSizeViaCrossAxisConstraints(
         transferredSizeSuggestion, aItemReflowInput);
 
-    FLEX_LOGV(" Transferred size suggestion: %d", transferredSizeSuggestion);
+    FLEX_LOGV("Transferred size suggestion: %d", transferredSizeSuggestion);
     return transferredSizeSuggestion;
   }
 
@@ -1638,8 +1650,10 @@ void nsFlexContainerFrame::ResolveAutoFlexBasisAndMinSize(
     return;
   }
 
-  FLEX_LOGV("Resolving auto main size or auto min main size for flex item %p",
-            aFlexItem.Frame());
+  FLEX_ITEM_LOG(
+      aFlexItem.Frame(),
+      "Resolving auto main size? %s; resolving auto min main size? %s",
+      BoolToYesNo(isMainSizeAuto), BoolToYesNo(isMainMinSizeAuto));
 
   nscoord resolvedMinSize;  // (only set/used if isMainMinSizeAuto==true)
   bool minSizeNeedsToMeasureContent = false;  // assume the best
@@ -1725,7 +1739,7 @@ void nsFlexContainerFrame::ResolveAutoFlexBasisAndMinSize(
             contentSizeSuggestion, aItemReflowInput);
       }
 
-      FLEX_LOGV(" Content size suggestion: %d", contentSizeSuggestion);
+      FLEX_LOGV("Content size suggestion: %d", contentSizeSuggestion);
       resolvedMinSize = std::min(resolvedMinSize, contentSizeSuggestion);
 
       // Clamp the resolved min main size by the max main size if it's definite.
@@ -1739,7 +1753,7 @@ void nsFlexContainerFrame::ResolveAutoFlexBasisAndMinSize(
         // nscoord_MAX sentinel value if we reach this point).
         resolvedMinSize = nscoord_MAX;
       }
-      FLEX_LOGV(" Resolved auto min main size: %d", resolvedMinSize);
+      FLEX_LOGV("Resolved auto min main size: %d", resolvedMinSize);
 
       if (resolvedMinSize == contentSizeSuggestion) {
         // When we are here, we've measured the item's content-based size, and
@@ -1992,12 +2006,16 @@ const CachedBAxisMeasurement& nsFlexContainerFrame::MeasureBSizeForFlexItem(
   if (cachedData && cachedData->mBAxisMeasurement) {
     if (!aItem.Frame()->IsSubtreeDirty() &&
         cachedData->mBAxisMeasurement->IsValidFor(aChildReflowInput)) {
-      FLEX_LOG("[perf] MeasureBSizeForFlexItem accepted cached value");
+      FLEX_ITEM_LOG(aItem.Frame(),
+                    "[perf] Accepted cached measurement: block-size %d",
+                    cachedData->mBAxisMeasurement->BSize());
       return *(cachedData->mBAxisMeasurement);
     }
-    FLEX_LOG("[perf] MeasureBSizeForFlexItem rejected cached value");
+    FLEX_ITEM_LOG(aItem.Frame(),
+                  "[perf] Rejected cached measurement: block-size %d",
+                  cachedData->mBAxisMeasurement->BSize());
   } else {
-    FLEX_LOG("[perf] MeasureBSizeForFlexItem didn't have a cached value");
+    FLEX_ITEM_LOG(aItem.Frame(), "[perf] No cached measurement");
   }
 
   // CachedFlexItemData is stored in item's writing mode, so we pass
@@ -2055,7 +2073,7 @@ void nsFlexContainerFrame::MarkIntrinsicISizesDirty() {
 nscoord nsFlexContainerFrame::MeasureFlexItemContentBSize(
     FlexItem& aFlexItem, bool aForceBResizeForMeasuringReflow,
     const ReflowInput& aParentReflowInput) {
-  FLEX_LOG("Measuring flex item's content block-size");
+  FLEX_ITEM_LOG(aFlexItem.Frame(), "Measuring item's content block-size");
 
   // Set up a reflow input for measuring the flex item's content block-size:
   WritingMode wm = aFlexItem.Frame()->GetWritingMode();
@@ -2070,7 +2088,7 @@ nscoord nsFlexContainerFrame::MeasureFlexItemContentBSize(
     // block-size, because that would prevent us from measuring the content
     // block-size.
     sizeOverrides.mAspectRatio.emplace(AspectRatio());
-    FLEX_LOGV(" Cross size override: %d", aFlexItem.CrossSize());
+    FLEX_LOGV("Cross size override: %d", aFlexItem.CrossSize());
   }
   sizeOverrides.mStyleBSize.emplace(StyleSize::Auto());
 
@@ -2234,7 +2252,7 @@ FlexItem::FlexItem(ReflowInput& aFlexItemReflowInput, float aFlexGrow,
       // getting the physical side that corresponds to these axes' "logical
       // start" sides, and we compare those physical sides to find out if
       // they're the same vs. opposite.
-      mozilla::Side itemBlockStartSide = mWM.PhysicalSide(eLogicalSideBStart);
+      mozilla::Side itemBlockStartSide = mWM.PhysicalSide(LogicalSide::BStart);
 
       // (Note: this is *not* the "flex-start" side; rather, it's the *logical*
       // i.e. WM-relative block-start or inline-start side.)
@@ -2363,7 +2381,7 @@ nscoord FlexItem::BaselineOffsetFromOuterCrossEdge(
              "Only expecting to be doing baseline computations when the "
              "cross axis is the block axis");
 
-  mozilla::Side itemBlockStartSide = mWM.PhysicalSide(eLogicalSideBStart);
+  mozilla::Side itemBlockStartSide = mWM.PhysicalSide(LogicalSide::BStart);
 
   nscoord marginBStartToBaseline = ResolvedAscent(aUseFirstLineBaseline) +
                                    PhysicalMargin().Side(itemBlockStartSide);
@@ -2537,18 +2555,17 @@ static bool FrameHasRelativeBSizeDependency(nsIFrame* aFrame) {
 
 bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   if (!StaticPrefs::layout_flexbox_item_final_reflow_optimization_enabled()) {
-    FLEX_LOG(
-        "[perf] Flex item %p needed a final reflow due to optimization being "
-        "disabled via the preference",
-        mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[perf] Item needed a final reflow due to optimization being "
+                  "disabled via the preference");
     return true;
   }
 
   // NOTE: We can have continuations from an earlier constrained reflow.
   if (mFrame->GetPrevInFlow() || mFrame->GetNextInFlow()) {
     // This is an item has continuation(s). Reflow it.
-    FLEX_LOG("[frag] Flex item %p needed a final reflow due to continuation(s)",
-             mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[frag] Item needed a final reflow due to continuation(s)");
     return true;
   }
 
@@ -2560,10 +2577,9 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   // prevent triggering O(n^2) behavior when printing a deeply-nested flex
   // container.
   if (aParentReflowInput.IsInFragmentedContext()) {
-    FLEX_LOG(
-        "[frag] Flex item %p needed both a measuring reflow and a final "
-        "reflow due to being in a fragmented context.",
-        mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[frag] Item needed both a measuring reflow and a final "
+                  "reflow due to being in a fragmented context");
     return true;
   }
 
@@ -2579,10 +2595,9 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
     if (finalSize != mFrame->ContentSize(mWM)) {
       // The measuring reflow left the item with a different size than its
       // final flexed size. So, we need to reflow to give it the correct size.
-      FLEX_LOG(
-          "[perf] Flex item %p needed both a measuring reflow and a final "
-          "reflow due to measured size disagreeing with final size",
-          mFrame);
+      FLEX_ITEM_LOG(mFrame,
+                    "[perf] Item needed both a measuring reflow and a final "
+                    "reflow due to measured size disagreeing with final size");
       return true;
     }
 
@@ -2590,10 +2605,9 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
       // This item has descendants with relative BSizes who may care that its
       // size may now be considered "definite" in the final reflow (whereas it
       // was indefinite during the measuring reflow).
-      FLEX_LOG(
-          "[perf] Flex item %p needed both a measuring reflow and a final "
-          "reflow due to BSize potentially becoming definite",
-          mFrame);
+      FLEX_ITEM_LOG(mFrame,
+                    "[perf] Item needed both a measuring reflow and a final "
+                    "reflow due to BSize potentially becoming definite");
       return true;
     }
 
@@ -2621,10 +2635,9 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   // definiteness.
   // Let's check for each condition that would still require us to reflow:
   if (mFrame->IsSubtreeDirty()) {
-    FLEX_LOG(
-        "[perf] Flex item %p needed a final reflow due to its subtree "
-        "being dirty",
-        mFrame);
+    FLEX_ITEM_LOG(
+        mFrame,
+        "[perf] Item needed a final reflow due to its subtree being dirty");
     return true;
   }
 
@@ -2634,19 +2647,17 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   // Did we cache the metrics from its most recent "final reflow"?
   auto* cache = mFrame->GetProperty(CachedFlexItemData::Prop());
   if (!cache || !cache->mFinalReflowMetrics) {
-    FLEX_LOG(
-        "[perf] Flex item %p needed a final reflow due to lacking a "
-        "cached mFinalReflowMetrics (maybe cache was cleared)",
-        mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[perf] Item needed a final reflow due to lacking a cached "
+                  "mFinalReflowMetrics (maybe cache was cleared)");
     return true;
   }
 
   // Does the cached size match our current size?
   if (cache->mFinalReflowMetrics->Size() != finalSize) {
-    FLEX_LOG(
-        "[perf] Flex item %p needed a final reflow due to having a "
-        "different content box size vs. its most recent final reflow",
-        mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[perf] Item needed a final reflow due to having a different "
+                  "content box size vs. its most recent final reflow");
     return true;
   }
 
@@ -2659,10 +2670,9 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   // reflow.
   if (cache->mFinalReflowMetrics->BorderPadding() !=
       BorderPadding().ConvertTo(mWM, mCBWM)) {
-    FLEX_LOG(
-        "[perf] Flex item %p needed a final reflow due to having a "
-        "different border and padding vs. its most recent final reflow",
-        mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[perf] Item needed a final reflow due to having a different "
+                  "border and padding vs. its most recent final reflow");
     return true;
   }
 
@@ -2672,10 +2682,9 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   if (cache->mFinalReflowMetrics->TreatBSizeAsIndefinite() !=
           mTreatBSizeAsIndefinite &&
       FrameHasRelativeBSizeDependency(mFrame)) {
-    FLEX_LOG(
-        "[perf] Flex item %p needed a final reflow due to having "
-        "its BSize change definiteness & having a rel-BSize child",
-        mFrame);
+    FLEX_ITEM_LOG(mFrame,
+                  "[perf] Item needed a final reflow due to having its BSize "
+                  "change definiteness & having a rel-BSize child");
     return true;
   }
 
@@ -2683,7 +2692,7 @@ bool FlexItem::NeedsFinalReflow(const ReflowInput& aParentReflowInput) const {
   // dirty, and our current conditions are sufficiently similar to the most
   // recent "final reflow" that it should have left our subtree in the correct
   // state.)
-  FLEX_LOG("[perf] Flex item %p didn't need a final reflow", mFrame);
+  FLEX_ITEM_LOG(mFrame, "[perf] Item didn't need a final reflow");
   return false;
 }
 
@@ -2757,7 +2766,7 @@ class MOZ_STACK_CLASS PositionTracker {
   const WritingMode mWM;
 
   // The axis along which we're moving.
-  const LogicalAxis mAxis = eLogicalAxisInline;
+  const LogicalAxis mAxis = LogicalAxis::Inline;
 
   // Is the axis along which we're moving reversed (e.g. LTR vs RTL) with
   // respect to the corresponding axis on the flex container's WM?
@@ -3150,8 +3159,8 @@ void FlexLine::ResolveFlexibleLengths(nscoord aFlexContainerMainSize,
       availableFreeSpace -= item.MainSize();
     }
 
-    FLEX_LOG(" available free space: %" PRId64 "; flex items should \"%s\"",
-             availableFreeSpace.value, isUsingFlexGrow ? "grow" : "shrink");
+    FLEX_LOGV("Available free space: %" PRId64 "; flex items should \"%s\"",
+              availableFreeSpace.value, isUsingFlexGrow ? "grow" : "shrink");
 
     // The sign of our free space should agree with the type of flexing
     // (grow/shrink) that we're doing. Any disagreement should've made us use
@@ -3276,7 +3285,7 @@ void FlexLine::ResolveFlexibleLengths(nscoord aFlexContainerMainSize,
           }
         }
 
-        FLEX_LOG(" Distributing available space:");
+        FLEX_LOGV("Distributing available space:");
         // Since this loop only operates on unfrozen flex items, we can break as
         // soon as we have seen all of them.
         numUnfrozenItemsToBeSeen = NumItems() - mNumFrozenItems;
@@ -3323,8 +3332,8 @@ void FlexLine::ResolveFlexibleLengths(nscoord aFlexContainerMainSize,
 
             item.SetMainSize(item.MainSize() +
                              nscoord(sizeDelta.ToMinMaxClamped()));
-            FLEX_LOG("  flex item %p receives %" PRId64 ", for a total of %d",
-                     item.Frame(), sizeDelta.value, item.MainSize());
+            FLEX_LOGV("  Flex item %p receives %" PRId64 ", for a total of %d",
+                      item.Frame(), sizeDelta.value, item.MainSize());
           }
         }
 
@@ -3360,7 +3369,7 @@ void FlexLine::ResolveFlexibleLengths(nscoord aFlexContainerMainSize,
 
     // Fix min/max violations:
     nscoord totalViolation = 0;  // keeps track of adjustments for min/max
-    FLEX_LOG(" Checking for violations:");
+    FLEX_LOGV("Checking for violations:");
 
     // Since this loop only operates on unfrozen flex items, we can break as
     // soon as we have seen all of them.
@@ -3392,7 +3401,7 @@ void FlexLine::ResolveFlexibleLengths(nscoord aFlexContainerMainSize,
     FreezeOrRestoreEachFlexibleSize(totalViolation,
                                     iterationCounter + 1 == NumItems());
 
-    FLEX_LOG(" Total violation: %d", totalViolation);
+    FLEX_LOGV("Total violation: %d", totalViolation);
 
     if (mNumFrozenItems == NumItems()) {
       break;
@@ -3952,7 +3961,7 @@ void SingleLineCrossAxisPositionTracker::EnterAlignPackingSpace(
   if (alignSelf == StyleAlignFlags::SELF_START ||
       alignSelf == StyleAlignFlags::SELF_END) {
     const LogicalAxis logCrossAxis =
-        aAxisTracker.IsRowOriented() ? eLogicalAxisBlock : eLogicalAxisInline;
+        aAxisTracker.IsRowOriented() ? LogicalAxis::Block : LogicalAxis::Inline;
     const WritingMode cWM = aAxisTracker.GetWritingMode();
     const bool sameStart =
         cWM.ParallelAxisStartsOnSameSide(logCrossAxis, aItem.GetWritingMode());
@@ -4560,7 +4569,6 @@ void nsFlexContainerFrame::Reflow(nsPresContext* aPresContext,
 
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsFlexContainerFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   MOZ_ASSERT(aPresContext == PresContext());
   NS_WARNING_ASSERTION(
@@ -4568,7 +4576,7 @@ void nsFlexContainerFrame::Reflow(nsPresContext* aPresContext,
       "Unconstrained inline size; this should only result from huge sizes "
       "(not intrinsic sizing w/ orthogonal flows)");
 
-  FLEX_LOG("Reflow() for nsFlexContainerFrame %p", this);
+  FLEX_LOG("Reflowing flex container frame %p ...", this);
 
   if (IsFrameTreeTooDeep(aReflowInput, aReflowOutput, aStatus)) {
     return;
@@ -5276,8 +5284,8 @@ nsFlexContainerFrame::FlexLayoutResult nsFlexContainerFrame::DoFlexLayout(
         } else {
           sizeOverrides.mStyleBSize.emplace(item.StyleMainSize());
         }
-        FLEX_LOG("Sizing flex item %p in cross axis", item.Frame());
-        FLEX_LOGV(" Main size override: %d", item.MainSize());
+        FLEX_ITEM_LOG(item.Frame(), "Sizing item in cross axis");
+        FLEX_LOGV("Main size override: %d", item.MainSize());
 
         const WritingMode wm = item.GetWritingMode();
         LogicalSize availSize = aReflowInput.ComputedSize(wm);
@@ -5640,10 +5648,10 @@ std::tuple<nscoord, nsReflowStatus> nsFlexContainerFrame::ReflowChildren(
         // block-size and add it to
         // PerFragmentFlexData::mCumulativeContentBoxBSize even if we are not
         // laying out any child.
-        FLEX_LOG(
-            "[frag] Flex item %p needed to be pushed to container's "
-            "next-in-flow due to position below available space's block-end",
-            item.Frame());
+        FLEX_ITEM_LOG(
+            item.Frame(),
+            "[frag] Item needed to be pushed to container's next-in-flow due "
+            "to being positioned beyond block-end edge of available space");
         pushedItems.Insert(item.Frame());
         itemInPushedItems = true;
       } else if (item.NeedsFinalReflow(aReflowInput)) {
@@ -5680,11 +5688,10 @@ std::tuple<nscoord, nsReflowStatus> nsFlexContainerFrame::ReflowChildren(
           return true;
         }();
         if (shouldPushItem) {
-          FLEX_LOG(
-              "[frag] Flex item %p needed to be pushed to container's "
-              "next-in-flow because its block-size is larger than the "
-              "available space",
-              item.Frame());
+          FLEX_ITEM_LOG(
+              item.Frame(),
+              "[frag] Item needed to be pushed to container's next-in-flow "
+              "because its block-size is larger than the available space");
           pushedItems.Insert(item.Frame());
           itemInPushedItems = true;
         } else if (childReflowStatus.IsIncomplete()) {
@@ -6050,8 +6057,8 @@ void nsFlexContainerFrame::MoveFlexItemToFinalPosition(
                                           logicalOffsets, &pos, aContainerSize);
   }
 
-  FLEX_LOG("Moving flex item %p to its desired position %s", aItem.Frame(),
-           ToString(pos).c_str());
+  FLEX_ITEM_LOG(aItem.Frame(), "Moving item to its desired position %s",
+                ToString(pos).c_str());
   aItem.Frame()->SetPosition(outerWM, pos, aContainerSize);
   PositionFrameView(aItem.Frame());
   PositionChildViews(aItem.Frame());
@@ -6061,7 +6068,7 @@ nsReflowStatus nsFlexContainerFrame::ReflowFlexItem(
     const FlexboxAxisTracker& aAxisTracker, const ReflowInput& aReflowInput,
     const FlexItem& aItem, const LogicalPoint& aFramePos,
     const LogicalSize& aAvailableSize, const nsSize& aContainerSize) {
-  FLEX_LOG("Doing final reflow for flex item %p", aItem.Frame());
+  FLEX_ITEM_LOG(aItem.Frame(), "Doing final reflow");
 
   // Returns true if we should use 'auto' in block axis's StyleSizeOverrides to
   // allow fragmentation-imposed block-size growth.
@@ -6131,15 +6138,15 @@ nsReflowStatus nsFlexContainerFrame::ReflowFlexItem(
   // Override flex item's main size.
   if (aItem.IsInlineAxisMainAxis()) {
     sizeOverrides.mStyleISize.emplace(aItem.StyleMainSize());
-    FLEX_LOGV(" Main size (inline-size) override: %d", aItem.MainSize());
+    FLEX_LOGV("Main size (inline-size) override: %d", aItem.MainSize());
   } else {
     overrideBSizeWithAuto = ComputeBSizeOverrideWithAuto();
     if (overrideBSizeWithAuto) {
       sizeOverrides.mStyleBSize.emplace(StyleSize::Auto());
-      FLEX_LOGV(" Main size (block-size) override: Auto");
+      FLEX_LOGV("Main size (block-size) override: Auto");
     } else {
       sizeOverrides.mStyleBSize.emplace(aItem.StyleMainSize());
-      FLEX_LOGV(" Main size (block-size) override: %d", aItem.MainSize());
+      FLEX_LOGV("Main size (block-size) override: %d", aItem.MainSize());
     }
   }
 
@@ -6148,15 +6155,15 @@ nsReflowStatus nsFlexContainerFrame::ReflowFlexItem(
   if (aItem.IsStretched()) {
     if (aItem.IsInlineAxisCrossAxis()) {
       sizeOverrides.mStyleISize.emplace(aItem.StyleCrossSize());
-      FLEX_LOGV(" Cross size (inline-size) override: %d", aItem.CrossSize());
+      FLEX_LOGV("Cross size (inline-size) override: %d", aItem.CrossSize());
     } else {
       overrideBSizeWithAuto = ComputeBSizeOverrideWithAuto();
       if (overrideBSizeWithAuto) {
         sizeOverrides.mStyleBSize.emplace(StyleSize::Auto());
-        FLEX_LOGV(" Cross size (block-size) override: Auto");
+        FLEX_LOGV("Cross size (block-size) override: Auto");
       } else {
         sizeOverrides.mStyleBSize.emplace(aItem.StyleCrossSize());
-        FLEX_LOGV(" Cross size (block-size) override: %d", aItem.CrossSize());
+        FLEX_LOGV("Cross size (block-size) override: %d", aItem.CrossSize());
       }
     }
   }
@@ -6203,8 +6210,8 @@ nsReflowStatus nsFlexContainerFrame::ReflowFlexItem(
   // after this point, because some of its methods (e.g. SetComputedWidth)
   // internally call InitResizeFlags and stomp on mVResize & mHResize.
 
-  FLEX_LOG("Reflowing flex item %p at its desired position %s", aItem.Frame(),
-           ToString(aFramePos).c_str());
+  FLEX_ITEM_LOG(aItem.Frame(), "Reflowing item at its desired position %s",
+                ToString(aFramePos).c_str());
 
   // CachedFlexItemData is stored in item's writing mode, so we pass
   // aChildReflowInput into ReflowOutput's constructor.
@@ -6332,7 +6339,6 @@ nscoord nsFlexContainerFrame::IntrinsicISize(gfxContext* aRenderingContext,
 
 /* virtual */
 nscoord nsFlexContainerFrame::GetMinISize(gfxContext* aRenderingContext) {
-  DISPLAY_MIN_INLINE_SIZE(this, mCachedMinISize);
   if (mCachedMinISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
     if (Maybe<nscoord> containISize = ContainIntrinsicISize()) {
       mCachedMinISize = *containISize;
@@ -6347,7 +6353,6 @@ nscoord nsFlexContainerFrame::GetMinISize(gfxContext* aRenderingContext) {
 
 /* virtual */
 nscoord nsFlexContainerFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  DISPLAY_PREF_INLINE_SIZE(this, mCachedPrefISize);
   if (mCachedPrefISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
     if (Maybe<nscoord> containISize = ContainIntrinsicISize()) {
       mCachedPrefISize = *containISize;
diff --git a/layout/generic/nsFlexContainerFrame.h b/layout/generic/nsFlexContainerFrame.h
index 30e440b401..14f91ae064 100644
--- a/layout/generic/nsFlexContainerFrame.h
+++ b/layout/generic/nsFlexContainerFrame.h
@@ -12,15 +12,9 @@
 #include <tuple>
 
 #include "mozilla/dom/FlexBinding.h"
-#include "mozilla/UniquePtr.h"
 #include "nsContainerFrame.h"
 #include "nsILineIterator.h"
 
-namespace mozilla {
-class LogicalPoint;
-class PresShell;
-}  // namespace mozilla
-
 nsContainerFrame* NS_NewFlexContainerFrame(mozilla::PresShell* aPresShell,
                                            mozilla::ComputedStyle* aStyle);
 
diff --git a/layout/generic/nsFloatManager.cpp b/layout/generic/nsFloatManager.cpp
index b6612ca6f5..e1866b35c1 100644
--- a/layout/generic/nsFloatManager.cpp
+++ b/layout/generic/nsFloatManager.cpp
@@ -2507,7 +2507,7 @@ nsFloatManager::ShapeInfo::CreateBasicShape(const StyleBasicShape& aBasicShape,
     case StyleBasicShape::Tag::Rect:
       return CreateInset(aBasicShape, aShapeMargin, aFrame, aShapeBoxRect, aWM,
                          aContainerSize);
-    case StyleBasicShape::Tag::Path:
+    case StyleBasicShape::Tag::PathOrShape:
       MOZ_ASSERT_UNREACHABLE("Unsupported basic shape");
   }
   return nullptr;
diff --git a/layout/generic/nsFrameSelection.cpp b/layout/generic/nsFrameSelection.cpp
index f1a8c7e27c..ca4e3d647e 100644
--- a/layout/generic/nsFrameSelection.cpp
+++ b/layout/generic/nsFrameSelection.cpp
@@ -156,9 +156,10 @@ PeekOffsetStruct::PeekOffsetStruct(nsSelectionAmount aAmount,
 
 }  // namespace mozilla
 
-// Array which contains index of each SelecionType in Selection::mDOMSelections.
-// For avoiding using if nor switch to retrieve the index, this needs to have
-// -1 for SelectionTypes which won't be created its Selection instance.
+// Array which contains index of each SelectionType in
+// Selection::mDOMSelections. For avoiding using if nor switch to retrieve the
+// index, this needs to have -1 for SelectionTypes which won't be created its
+// Selection instance.
 static const int8_t kIndexOfSelections[] = {
     -1,  // SelectionType::eInvalid
     -1,  // SelectionType::eNone
@@ -172,6 +173,7 @@ static const int8_t kIndexOfSelections[] = {
     7,   // SelectionType::eFind
     8,   // SelectionType::eURLSecondary
     9,   // SelectionType::eURLStrikeout
+    10,  // SelectionType::eTargetText
     -1,  // SelectionType::eHighlight
 };
 
@@ -539,7 +541,11 @@ nsresult nsFrameSelection::ConstrainFrameAndPointToAnchorSubtree(
 
   NS_ENSURE_STATE(mPresShell);
   RefPtr<PresShell> presShell = mPresShell;
-  nsIContent* anchorRoot = anchorContent->GetSelectionRootContent(presShell);
+  nsIContent* anchorRoot =
+      anchorContent
+          ->GetSelectionRootContent(
+              presShell,
+              StaticPrefs::dom_shadowdom_selection_across_boundary_enabled() /* aAllowCrossShadowBoundary */);
   NS_ENSURE_TRUE(anchorRoot, NS_ERROR_UNEXPECTED);
 
   //
@@ -549,7 +555,10 @@ nsresult nsFrameSelection::ConstrainFrameAndPointToAnchorSubtree(
   nsCOMPtr<nsIContent> content = aFrame->GetContent();
 
   if (content) {
-    nsIContent* contentRoot = content->GetSelectionRootContent(presShell);
+    nsIContent* contentRoot =
+        content->GetSelectionRootContent(
+            presShell, StaticPrefs::
+                           dom_shadowdom_selection_across_boundary_enabled() /* aAllowCrossShadowBoundary */);
     NS_ENSURE_TRUE(contentRoot, NS_ERROR_UNEXPECTED);
 
     if (anchorRoot == contentRoot) {
@@ -573,8 +582,9 @@ nsresult nsFrameSelection::ConstrainFrameAndPointToAnchorSubtree(
       if (cursorFrame && cursorFrame->PresShell() == presShell) {
         nsCOMPtr<nsIContent> cursorContent = cursorFrame->GetContent();
         NS_ENSURE_TRUE(cursorContent, NS_ERROR_FAILURE);
-        nsIContent* cursorContentRoot =
-            cursorContent->GetSelectionRootContent(presShell);
+        nsIContent* cursorContentRoot = cursorContent->GetSelectionRootContent(
+            presShell, StaticPrefs::
+                           dom_shadowdom_selection_across_boundary_enabled() /* aAllowCrossShadowBoundary */);
         NS_ENSURE_TRUE(cursorContentRoot, NS_ERROR_UNEXPECTED);
         if (cursorContentRoot == anchorRoot) {
           *aRetFrame = cursorFrame;
@@ -1493,11 +1503,11 @@ void nsFrameSelection::SetDragState(bool aState) {
     // Notify that reason is mouse up.
     SetChangeReasons(nsISelectionListener::MOUSEUP_REASON);
 
-    // flag is set to false in `NotifySelectionListeners`.
+    // flag is set to NotApplicable in `Selection::NotifySelectionListeners`.
     // since this function call is part of click event, this would immediately
     // reset the flag, rendering it useless.
-    AutoRestore<bool> restoreIsDoubleClickSelectionFlag(
-        mIsDoubleClickSelection);
+    AutoRestore<ClickSelectionType> restoreClickSelectionType(
+        mClickSelectionType);
     // Be aware, the Selection instance may be destroyed after this call.
     NotifySelectionListeners(SelectionType::eNormal);
   }
diff --git a/layout/generic/nsFrameSelection.h b/layout/generic/nsFrameSelection.h
index e8c55d53b5..3ba6fa72ca 100644
--- a/layout/generic/nsFrameSelection.h
+++ b/layout/generic/nsFrameSelection.h
@@ -200,6 +200,7 @@ class SelectionChangeEventDispatcher;
 namespace dom {
 class Highlight;
 class Selection;
+enum class ClickSelectionType { NotApplicable, Double, Triple };
 }  // namespace dom
 
 /**
@@ -259,14 +260,17 @@ class nsFrameSelection final {
 
  public:
   /**
-   * Sets flag to true if a selection is created by doubleclick or
-   * long tapping a word.
+   * Sets the type of the selection based on whether a selection is created
+   * by doubleclick, long tapping a word or tripleclick.
    *
-   * @param aIsDoubleClickSelection   True if the selection is created by
-   *                                  doubleclick or long tap over a word.
+   * @param aClickSelectionType   ClickSelectionType::Double if the selection
+   *                              is created by doubleclick,
+   *                              ClickSelectionType::Triple if the selection
+   *                              is created by tripleclick.
    */
-  void SetIsDoubleClickSelection(bool aIsDoubleClickSelection) {
-    mIsDoubleClickSelection = aIsDoubleClickSelection;
+  void SetClickSelectionType(
+      mozilla::dom::ClickSelectionType aClickSelectionType) {
+    mClickSelectionType = aClickSelectionType;
   }
 
   /**
@@ -274,7 +278,14 @@ class nsFrameSelection final {
    * long tap over a word.
    */
   [[nodiscard]] bool IsDoubleClickSelection() const {
-    return mIsDoubleClickSelection;
+    return mClickSelectionType == mozilla::dom::ClickSelectionType::Double;
+  }
+
+  /**
+   * Returns true if the selection was created by triple click
+   */
+  [[nodiscard]] bool IsTripleClickSelection() const {
+    return mClickSelectionType == mozilla::dom::ClickSelectionType::Triple;
   }
 
   /**
@@ -1102,11 +1113,12 @@ class nsFrameSelection final {
   bool mDragState = false;  // for drag purposes
   bool mAccessibleCaretEnabled = false;
 
-  // Records if a selection was created by doubleclicking a word.
-  // This information is needed later on to determine if a leading
+  // Records if a selection was created by doubleclicking or tripleclicking
+  // a word. This information is needed later on to determine if a leading
   // or trailing whitespace needs to be removed as well to achieve
   // native behaviour on macOS.
-  bool mIsDoubleClickSelection{false};
+  mozilla::dom::ClickSelectionType mClickSelectionType =
+      mozilla::dom::ClickSelectionType::NotApplicable;
 };
 
 /**
diff --git a/layout/generic/nsFrameSetFrame.cpp b/layout/generic/nsFrameSetFrame.cpp
index f292988c55..be561a6c32 100644
--- a/layout/generic/nsFrameSetFrame.cpp
+++ b/layout/generic/nsFrameSetFrame.cpp
@@ -760,7 +760,6 @@ void nsHTMLFramesetFrame::Reflow(nsPresContext* aPresContext,
                                  nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsHTMLFramesetFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   mozilla::PresShell* presShell = aPresContext->PresShell();
@@ -1312,7 +1311,6 @@ void nsHTMLFramesetBorderFrame::Reflow(nsPresContext* aPresContext,
                                        const ReflowInput& aReflowInput,
                                        nsReflowStatus& aStatus) {
   DO_GLOBAL_REFLOW_COUNT("nsHTMLFramesetBorderFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Override Reflow(), since we don't want to deal with what our
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index 361847b753..2b0c53efe1 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -170,7 +170,7 @@ class nsHTMLScrollFrame::ScrollEvent : public Runnable {
 class nsHTMLScrollFrame::ScrollEndEvent : public Runnable {
  public:
   NS_DECL_NSIRUNNABLE
-  explicit ScrollEndEvent(nsHTMLScrollFrame* aHelper);
+  explicit ScrollEndEvent(nsHTMLScrollFrame* aHelper, bool aDelayed);
   void Revoke() { mHelper = nullptr; }
 
  private:
@@ -1265,17 +1265,7 @@ nsMargin nsHTMLScrollFrame::ComputeStableScrollbarGutter(
 
 // Legacy, this sucks!
 static bool IsMarqueeScrollbox(const nsIFrame& aScrollFrame) {
-  if (!aScrollFrame.GetContent()) {
-    return false;
-  }
-  if (MOZ_LIKELY(!aScrollFrame.GetContent()->HasBeenInUAWidget())) {
-    return false;
-  }
-  MOZ_ASSERT(aScrollFrame.GetParent() &&
-             aScrollFrame.GetParent()->GetContent());
-  return aScrollFrame.GetParent() &&
-         HTMLMarqueeElement::FromNodeOrNull(
-             aScrollFrame.GetParent()->GetContent());
+  return HTMLMarqueeElement::FromNodeOrNull(aScrollFrame.GetContent());
 }
 
 /* virtual */
@@ -1290,7 +1280,6 @@ nscoord nsHTMLScrollFrame::GetMinISize(gfxContext* aRenderingContext) {
     return mScrolledFrame->GetMinISize(aRenderingContext);
   }();
 
-  DISPLAY_MIN_INLINE_SIZE(this, result);
   return result + IntrinsicScrollbarGutterSizeAtInlineEdges();
 }
 
@@ -1300,7 +1289,6 @@ nscoord nsHTMLScrollFrame::GetPrefISize(gfxContext* aRenderingContext) {
   nscoord result = containISize
                        ? *containISize
                        : mScrolledFrame->GetPrefISize(aRenderingContext);
-  DISPLAY_PREF_INLINE_SIZE(this, result);
   return NSCoordSaturatingAdd(result,
                               IntrinsicScrollbarGutterSizeAtInlineEdges());
 }
@@ -1497,7 +1485,6 @@ void nsHTMLScrollFrame::Reflow(nsPresContext* aPresContext,
                                nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsHTMLScrollFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   HandleScrollbarStyleSwitching();
@@ -5429,23 +5416,31 @@ nsresult nsHTMLScrollFrame::FireScrollPortEvent() {
   return EventDispatcher::Dispatch(content, presContext, &event);
 }
 
-void nsHTMLScrollFrame::PostScrollEndEvent() {
+void nsHTMLScrollFrame::PostScrollEndEvent(bool aDelayed) {
   if (mScrollEndEvent) {
     return;
   }
 
   // The ScrollEndEvent constructor registers itself with the refresh driver.
-  mScrollEndEvent = new ScrollEndEvent(this);
+  mScrollEndEvent = new ScrollEndEvent(this, aDelayed);
 }
 
 void nsHTMLScrollFrame::FireScrollEndEvent() {
-  MOZ_ASSERT(GetContent());
-  MOZ_ASSERT(mScrollEndEvent);
+  RefPtr<nsIContent> content = GetContent();
+  MOZ_ASSERT(content);
 
-  RefPtr<nsPresContext> presContext = PresContext();
+  MOZ_ASSERT(mScrollEndEvent);
   mScrollEndEvent->Revoke();
   mScrollEndEvent = nullptr;
 
+  if (content->GetComposedDoc() &&
+      content->GetComposedDoc()->EventHandlingSuppressed()) {
+    content->GetComposedDoc()->SetHasDelayedRefreshEvent();
+    PostScrollEndEvent(/* aDelayed = */ true);
+    return;
+  }
+
+  RefPtr<nsPresContext> presContext = PresContext();
   nsEventStatus status = nsEventStatus_eIgnore;
   WidgetGUIEvent event(true, eScrollend, nullptr);
   event.mFlags.mBubbles = mIsRoot;
@@ -5895,9 +5890,10 @@ nsHTMLScrollFrame::ScrollEvent::Run() {
   return NS_OK;
 }
 
-nsHTMLScrollFrame::ScrollEndEvent::ScrollEndEvent(nsHTMLScrollFrame* aHelper)
+nsHTMLScrollFrame::ScrollEndEvent::ScrollEndEvent(nsHTMLScrollFrame* aHelper,
+                                                  bool aDelayed)
     : Runnable("nsHTMLScrollFrame::ScrollEndEvent"), mHelper(aHelper) {
-  mHelper->PresContext()->RefreshDriver()->PostScrollEvent(this);
+  mHelper->PresContext()->RefreshDriver()->PostScrollEvent(this, aDelayed);
 }
 
 MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
diff --git a/layout/generic/nsGfxScrollFrame.h b/layout/generic/nsGfxScrollFrame.h
index ce2a75a3df..9d619de4e5 100644
--- a/layout/generic/nsGfxScrollFrame.h
+++ b/layout/generic/nsGfxScrollFrame.h
@@ -500,7 +500,7 @@ class nsHTMLScrollFrame : public nsContainerFrame,
   OverflowState GetOverflowState() const;
 
   MOZ_CAN_RUN_SCRIPT nsresult FireScrollPortEvent();
-  void PostScrollEndEvent();
+  void PostScrollEndEvent(bool aDelayed = false);
   MOZ_CAN_RUN_SCRIPT void FireScrollEndEvent();
   void PostOverflowEvent();
 
diff --git a/layout/generic/nsGridContainerFrame.cpp b/layout/generic/nsGridContainerFrame.cpp
index 5eb9cde7da..bb6e2150ce 100644
--- a/layout/generic/nsGridContainerFrame.cpp
+++ b/layout/generic/nsGridContainerFrame.cpp
@@ -28,6 +28,7 @@
 #include "nsCSSFrameConstructor.h"
 #include "nsDisplayList.h"
 #include "nsFieldSetFrame.h"
+#include "nsHTMLButtonControlFrame.h"
 #include "nsGfxScrollFrame.h"
 #include "nsHashKeys.h"
 #include "nsIFrameInlines.h"  // for nsIFrame::GetLogicalNormalPosition (don't remove)
@@ -168,7 +169,7 @@ static nscoord ResolveToDefiniteSize(const StyleTrackBreadth& aBreadth,
 // block axis; e.g. for English horizontal-tb text, a traditional baseline
 // would be a y-axis measurement.  But in some cases (e.g. orthogonal WMs), we
 // may need to synthesize a baseline in a child's inline axis, which is when
-// this function might receive an aAxis of eLogicalAxisInline. In that case, we
+// this function might receive an aAxis of LogicalAxis::Inline. In that case, we
 // assume that the writing mode's preference for central vs. alphabetic
 // baselines is irrelevant, since that's a choice about its block-axis
 // baselines, and we just unconditionally use the alphabetic baseline
@@ -178,7 +179,7 @@ static nscoord SynthesizeBaselineFromBorderBox(BaselineSharingGroup aGroup,
                                                LogicalAxis aAxis,
                                                nscoord aBorderBoxSize) {
   const bool useAlphabeticBaseline =
-      (aAxis == eLogicalAxisInline) ? true : aWM.IsAlphabeticalBaseline();
+      (aAxis == LogicalAxis::Inline) ? true : aWM.IsAlphabeticalBaseline();
 
   if (aGroup == BaselineSharingGroup::First) {
     return useAlphabeticBaseline ? aBorderBoxSize : aBorderBoxSize / 2;
@@ -218,7 +219,7 @@ struct RepeatTrackSizingInput {
         // We can use zero percentage basis since this is only called from
         // intrinsic sizing code.
         const nscoord percentageBasis = 0;
-        if (aAxis == eLogicalAxisInline) {
+        if (aAxis == LogicalAxis::Inline) {
           bp = std::max(padding.GetIStart(aWM).Resolve(percentageBasis), 0) +
                std::max(padding.GetIEnd(aWM).Resolve(percentageBasis), 0) +
                border.IStartEnd(aWM);
@@ -234,17 +235,17 @@ struct RepeatTrackSizingInput {
     nscoord& size = mSize.Size(aAxis, aWM);
     nscoord& max = mMax.Size(aAxis, aWM);
     const auto& minCoord =
-        aAxis == eLogicalAxisInline ? pos->MinISize(aWM) : pos->MinBSize(aWM);
+        aAxis == LogicalAxis::Inline ? pos->MinISize(aWM) : pos->MinBSize(aWM);
     if (minCoord.ConvertsToLength()) {
       min = adjustForBoxSizing(minCoord.ToLength());
     }
     const auto& maxCoord =
-        aAxis == eLogicalAxisInline ? pos->MaxISize(aWM) : pos->MaxBSize(aWM);
+        aAxis == LogicalAxis::Inline ? pos->MaxISize(aWM) : pos->MaxBSize(aWM);
     if (maxCoord.ConvertsToLength()) {
       max = std::max(min, adjustForBoxSizing(maxCoord.ToLength()));
     }
     const auto& sizeCoord =
-        aAxis == eLogicalAxisInline ? pos->ISize(aWM) : pos->BSize(aWM);
+        aAxis == LogicalAxis::Inline ? pos->ISize(aWM) : pos->BSize(aWM);
     if (sizeCoord.ConvertsToLength()) {
       size = Clamp(adjustForBoxSizing(sizeCoord.ToLength()), min, max);
     }
@@ -576,10 +577,10 @@ struct nsGridContainerFrame::GridArea {
       : mCols(aCols), mRows(aRows) {}
   bool IsDefinite() const { return mCols.IsDefinite() && mRows.IsDefinite(); }
   LineRange& LineRangeForAxis(LogicalAxis aAxis) {
-    return aAxis == eLogicalAxisInline ? mCols : mRows;
+    return aAxis == LogicalAxis::Inline ? mCols : mRows;
   }
   const LineRange& LineRangeForAxis(LogicalAxis aAxis) const {
-    return aAxis == eLogicalAxisInline ? mCols : mRows;
+    return aAxis == LogicalAxis::Inline ? mCols : mRows;
   }
   LineRange mCols;
   LineRange mRows;
@@ -665,12 +666,12 @@ struct nsGridContainerFrame::GridItemInfo {
    */
   GridItemInfo Transpose() const {
     GridItemInfo info(mFrame, GridArea(mArea.mRows, mArea.mCols));
-    info.mState[eLogicalAxisBlock] = mState[eLogicalAxisInline];
-    info.mState[eLogicalAxisInline] = mState[eLogicalAxisBlock];
-    info.mBaselineOffset[eLogicalAxisBlock] =
-        mBaselineOffset[eLogicalAxisInline];
-    info.mBaselineOffset[eLogicalAxisInline] =
-        mBaselineOffset[eLogicalAxisBlock];
+    info.mState[LogicalAxis::Block] = mState[LogicalAxis::Inline];
+    info.mState[LogicalAxis::Inline] = mState[LogicalAxis::Block];
+    info.mBaselineOffset[LogicalAxis::Block] =
+        mBaselineOffset[LogicalAxis::Inline];
+    info.mBaselineOffset[LogicalAxis::Inline] =
+        mBaselineOffset[LogicalAxis::Block];
     return info;
   }
 
@@ -684,7 +685,7 @@ struct nsGridContainerFrame::GridItemInfo {
 
   // Is this item a subgrid in either axis?
   bool IsSubgrid() const {
-    return IsSubgrid(eLogicalAxisInline) || IsSubgrid(eLogicalAxisBlock);
+    return IsSubgrid(LogicalAxis::Inline) || IsSubgrid(LogicalAxis::Block);
   }
 
   // Return the (inner) grid container frame associated with this subgrid item.
@@ -725,7 +726,7 @@ struct nsGridContainerFrame::GridItemInfo {
   bool ShouldApplyAutoMinSize(WritingMode aContainerWM,
                               LogicalAxis aContainerAxis,
                               nscoord aPercentageBasis) const {
-    const bool isInlineAxis = aContainerAxis == eLogicalAxisInline;
+    const bool isInlineAxis = aContainerAxis == LogicalAxis::Inline;
     const auto* pos =
         mFrame->IsTableWrapperFrame()
             ? mFrame->PrincipalChildList().FirstChild()->StylePosition()
@@ -793,9 +794,9 @@ struct nsGridContainerFrame::GridItemInfo {
       return isContinuationA;
     }
     auto masonryA = a->mArea.mRows.mStart;
-    auto gridA = a->mState[eLogicalAxisInline] & StateBits::eAutoPlacement;
+    auto gridA = a->mState[LogicalAxis::Inline] & StateBits::eAutoPlacement;
     auto masonryB = b->mArea.mRows.mStart;
-    auto gridB = b->mState[eLogicalAxisInline] & StateBits::eAutoPlacement;
+    auto gridB = b->mState[LogicalAxis::Inline] & StateBits::eAutoPlacement;
     return (masonryA == 0 ? masonryB != 0 : (masonryB != 0 && gridA < gridB)) &&
            !a->mFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW);
   }
@@ -804,9 +805,9 @@ struct nsGridContainerFrame::GridItemInfo {
     MOZ_ASSERT(!a->mFrame->GetPrevInFlow() && !b->mFrame->GetPrevInFlow(),
                "fragmentation not supported in inline axis");
     auto masonryA = a->mArea.mCols.mStart;
-    auto gridA = a->mState[eLogicalAxisBlock] & StateBits::eAutoPlacement;
+    auto gridA = a->mState[LogicalAxis::Block] & StateBits::eAutoPlacement;
     auto masonryB = b->mArea.mCols.mStart;
-    auto gridB = b->mState[eLogicalAxisBlock] & StateBits::eAutoPlacement;
+    auto gridB = b->mState[LogicalAxis::Block] & StateBits::eAutoPlacement;
     return (masonryA == 0 ? masonryB != 0 : (masonryB != 0 && gridA < gridB)) &&
            !a->mFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW);
   }
@@ -847,20 +848,20 @@ MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(ItemState)
 
 GridItemInfo::GridItemInfo(nsIFrame* aFrame, const GridArea& aArea)
     : mFrame(aFrame), mArea(aArea), mBaselineOffset{0, 0} {
-  mState[eLogicalAxisBlock] =
+  mState[LogicalAxis::Block] =
       StateBits(mArea.mRows.mStart == kAutoLine ? eAutoPlacement : 0);
-  mState[eLogicalAxisInline] =
+  mState[LogicalAxis::Inline] =
       StateBits(mArea.mCols.mStart == kAutoLine ? eAutoPlacement : 0);
 
   if (auto* gridFrame = GetGridContainerFrame(mFrame)) {
     auto parentWM = aFrame->GetParent()->GetWritingMode();
     bool isOrthogonal = parentWM.IsOrthogonalTo(gridFrame->GetWritingMode());
     if (gridFrame->IsColSubgrid()) {
-      mState[isOrthogonal ? eLogicalAxisBlock : eLogicalAxisInline] |=
+      mState[isOrthogonal ? LogicalAxis::Block : LogicalAxis::Inline] |=
           StateBits::eIsSubgrid;
     }
     if (gridFrame->IsRowSubgrid()) {
-      mState[isOrthogonal ? eLogicalAxisInline : eLogicalAxisBlock] |=
+      mState[isOrthogonal ? LogicalAxis::Inline : LogicalAxis::Block] |=
           StateBits::eIsSubgrid;
     }
   }
@@ -884,7 +885,7 @@ void GridItemInfo::InhibitSubgrid(nsGridContainerFrame* aParent,
   MOZ_ASSERT(IsSubgrid(aAxis));
   auto bit = NS_STATE_GRID_IS_COL_SUBGRID;
   if (aParent->GetWritingMode().IsOrthogonalTo(mFrame->GetWritingMode()) !=
-      (aAxis == eLogicalAxisBlock)) {
+      (aAxis == LogicalAxis::Block)) {
     bit = NS_STATE_GRID_IS_ROW_SUBGRID;
   }
   MOZ_ASSERT(SubgridFrame()->HasAnyStateBits(bit));
@@ -894,16 +895,18 @@ void GridItemInfo::InhibitSubgrid(nsGridContainerFrame* aParent,
 
 void GridItemInfo::MaybeInhibitSubgridInMasonry(nsGridContainerFrame* aParent,
                                                 uint32_t aGridAxisTrackCount) {
-  if (IsSubgrid(eLogicalAxisInline) && aParent->IsMasonry(eLogicalAxisBlock) &&
-      mArea.mRows.mStart != 0 && mArea.mCols.Extent() != aGridAxisTrackCount &&
-      (mState[eLogicalAxisInline] & eAutoPlacement)) {
-    InhibitSubgrid(aParent, eLogicalAxisInline);
+  if (IsSubgrid(LogicalAxis::Inline) &&
+      aParent->IsMasonry(LogicalAxis::Block) && mArea.mRows.mStart != 0 &&
+      mArea.mCols.Extent() != aGridAxisTrackCount &&
+      (mState[LogicalAxis::Inline] & eAutoPlacement)) {
+    InhibitSubgrid(aParent, LogicalAxis::Inline);
     return;
   }
-  if (IsSubgrid(eLogicalAxisBlock) && aParent->IsMasonry(eLogicalAxisInline) &&
-      mArea.mCols.mStart != 0 && mArea.mRows.Extent() != aGridAxisTrackCount &&
-      (mState[eLogicalAxisBlock] & eAutoPlacement)) {
-    InhibitSubgrid(aParent, eLogicalAxisBlock);
+  if (IsSubgrid(LogicalAxis::Block) &&
+      aParent->IsMasonry(LogicalAxis::Inline) && mArea.mCols.mStart != 0 &&
+      mArea.mRows.Extent() != aGridAxisTrackCount &&
+      (mState[LogicalAxis::Block] & eAutoPlacement)) {
+    InhibitSubgrid(aParent, LogicalAxis::Block);
   }
 }
 
@@ -1061,9 +1064,9 @@ void nsGridContainerFrame::GridItemInfo::Dump() const {
     printf("\n");
   };
   printf("grid-row: %d %d\n", mArea.mRows.mStart, mArea.mRows.mEnd);
-  Dump1("  grid block-axis: ", eLogicalAxisBlock);
+  Dump1("  grid block-axis: ", LogicalAxis::Block);
   printf("grid-column: %d %d\n", mArea.mCols.mStart, mArea.mCols.mEnd);
-  Dump1("  grid inline-axis: ", eLogicalAxisInline);
+  Dump1("  grid inline-axis: ", LogicalAxis::Inline);
 }
 #endif
 
@@ -1150,8 +1153,9 @@ struct nsGridContainerFrame::TrackSizingFunctions {
           parent->GetWritingMode().ParallelAxisStartsOnSameSide(parentAxis,
                                                                 grandParentWM);
       if (MOZ_UNLIKELY(!isSameDirInAxis)) {
-        auto end = parentAxis == eLogicalAxisBlock ? parentSubgrid->mGridRowEnd
-                                                   : parentSubgrid->mGridColEnd;
+        auto end = parentAxis == LogicalAxis::Block
+                       ? parentSubgrid->mGridRowEnd
+                       : parentSubgrid->mGridColEnd;
         range.ReverseDirection(end);
         // range is now in the same direction as the grand-parent's axis
       }
@@ -1166,7 +1170,7 @@ struct nsGridContainerFrame::TrackSizingFunctions {
       parent = grandParent;
     }
     const auto* pos = parent->StylePosition();
-    const auto isInlineAxis = parentAxis == eLogicalAxisInline;
+    const auto isInlineAxis = parentAxis == LogicalAxis::Inline;
     const auto& szf =
         isInlineAxis ? pos->mGridTemplateRows : pos->mGridTemplateColumns;
     const auto& autoSizing =
@@ -2707,7 +2711,7 @@ struct nsGridContainerFrame::Tracks {
    * gap before aRow to zero (and shift all rows after it by the removed gap).
    */
   void BreakBeforeRow(uint32_t aRow) {
-    MOZ_ASSERT(mAxis == eLogicalAxisBlock,
+    MOZ_ASSERT(mAxis == LogicalAxis::Block,
                "Should only be fragmenting in the block axis (between rows)");
     nscoord prevRowEndPos = 0;
     if (aRow != 0) {
@@ -2728,7 +2732,7 @@ struct nsGridContainerFrame::Tracks {
    * Set the size of aRow to aSize and adjust the position of all rows after it.
    */
   void ResizeRow(uint32_t aRow, nscoord aNewSize) {
-    MOZ_ASSERT(mAxis == eLogicalAxisBlock,
+    MOZ_ASSERT(mAxis == LogicalAxis::Block,
                "Should only be fragmenting in the block axis (between rows)");
     MOZ_ASSERT(aNewSize >= 0);
     auto& sz = mSizes[aRow];
@@ -2775,7 +2779,7 @@ struct nsGridContainerFrame::Tracks {
 #ifdef DEBUG
 void nsGridContainerFrame::Tracks::Dump() const {
   printf("%zu %s %s ", mSizes.Length(), mIsMasonry ? "masonry" : "grid",
-         mAxis == eLogicalAxisBlock ? "rows" : "columns");
+         mAxis == LogicalAxis::Block ? "rows" : "columns");
   TrackSize::DumpStateBits(mStateUnion);
   printf("\n");
   for (uint32_t i = 0, len = mSizes.Length(); i < len; ++i) {
@@ -2805,8 +2809,8 @@ void nsGridContainerFrame::Tracks::Dump() const {
  */
 struct nsGridContainerFrame::SharedGridData {
   SharedGridData()
-      : mCols(eLogicalAxisInline),
-        mRows(eLogicalAxisBlock),
+      : mCols(LogicalAxis::Inline),
+        mRows(LogicalAxis::Block),
         mGenerateComputedGridInfo(false) {}
   Tracks mCols;
   Tracks mRows;
@@ -2884,7 +2888,7 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
       }
     }
     if (mStartRow == numRows ||
-        aGridContainerFrame->IsMasonry(eLogicalAxisBlock)) {
+        aGridContainerFrame->IsMasonry(LogicalAxis::Block)) {
       // All of the grid's rows fit inside of previous grid-container fragments,
       // or it's a masonry axis.
       mFragBStart = aConsumedBSize;
@@ -2904,8 +2908,8 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
         aGridContainerFrame->SetProperty(UsedTrackSizes::Prop(), prop);
       }
       prop->mCanResolveLineRangeSize = {true, true};
-      prop->mSizes[eLogicalAxisInline].Assign(mCols.mSizes);
-      prop->mSizes[eLogicalAxisBlock].Assign(mRows.mSizes);
+      prop->mSizes[LogicalAxis::Inline].Assign(mCols.mSizes);
+      prop->mSizes[LogicalAxis::Block].Assign(mRows.mSizes);
     }
 
     // Copy item data from each child's first-in-flow data in mSharedGridData.
@@ -2921,18 +2925,19 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
               mGridItems.AppendElement(GridItemInfo(child, itemInfo.mArea));
           // Copy the item's baseline data so that the item's last fragment can
           // do 'last baseline' alignment if necessary.
-          item->mState[eLogicalAxisBlock] |=
-              itemInfo.mState[eLogicalAxisBlock] & ItemState::eAllBaselineBits;
-          item->mState[eLogicalAxisInline] |=
-              itemInfo.mState[eLogicalAxisInline] & ItemState::eAllBaselineBits;
-          item->mBaselineOffset[eLogicalAxisBlock] =
-              itemInfo.mBaselineOffset[eLogicalAxisBlock];
-          item->mBaselineOffset[eLogicalAxisInline] =
-              itemInfo.mBaselineOffset[eLogicalAxisInline];
-          item->mState[eLogicalAxisBlock] |=
-              itemInfo.mState[eLogicalAxisBlock] & ItemState::eAutoPlacement;
-          item->mState[eLogicalAxisInline] |=
-              itemInfo.mState[eLogicalAxisInline] & ItemState::eAutoPlacement;
+          item->mState[LogicalAxis::Block] |=
+              itemInfo.mState[LogicalAxis::Block] & ItemState::eAllBaselineBits;
+          item->mState[LogicalAxis::Inline] |=
+              itemInfo.mState[LogicalAxis::Inline] &
+              ItemState::eAllBaselineBits;
+          item->mBaselineOffset[LogicalAxis::Block] =
+              itemInfo.mBaselineOffset[LogicalAxis::Block];
+          item->mBaselineOffset[LogicalAxis::Inline] =
+              itemInfo.mBaselineOffset[LogicalAxis::Inline];
+          item->mState[LogicalAxis::Block] |=
+              itemInfo.mState[LogicalAxis::Block] & ItemState::eAutoPlacement;
+          item->mState[LogicalAxis::Inline] |=
+              itemInfo.mState[LogicalAxis::Inline] & ItemState::eAutoPlacement;
           break;
         }
       }
@@ -2975,7 +2980,7 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
 
   /**
    * Return the percentage basis for a grid item in its writing-mode.
-   * If aAxis is eLogicalAxisInline then we return NS_UNCONSTRAINEDSIZE in
+   * If aAxis is LogicalAxis::Inline then we return NS_UNCONSTRAINEDSIZE in
    * both axes since we know all track sizes are indefinite at this point
    * (we calculate column sizes before row sizes).  Otherwise, assert that
    * column sizes are known and calculate the size for aGridItem.mArea.mCols
@@ -3218,10 +3223,10 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
   }
 
   Tracks& TracksFor(LogicalAxis aAxis) {
-    return aAxis == eLogicalAxisBlock ? mRows : mCols;
+    return aAxis == LogicalAxis::Block ? mRows : mCols;
   }
   const Tracks& TracksFor(LogicalAxis aAxis) const {
-    return aAxis == eLogicalAxisBlock ? mRows : mCols;
+    return aAxis == LogicalAxis::Block ? mRows : mCols;
   }
 
   CSSOrderAwareFrameIterator mIter;
@@ -3275,13 +3280,13 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
                   const nsStylePosition* aGridStyle, const WritingMode& aWM)
       : mIter(aFrame, FrameChildListID::Principal),
         mGridStyle(aGridStyle),
-        mCols(eLogicalAxisInline),
-        mRows(eLogicalAxisBlock),
+        mCols(LogicalAxis::Inline),
+        mRows(LogicalAxis::Block),
         mColFunctions(mGridStyle->mGridTemplateColumns,
                       mGridStyle->mGridAutoColumns,
-                      aFrame->IsSubgrid(eLogicalAxisInline)),
+                      aFrame->IsSubgrid(LogicalAxis::Inline)),
         mRowFunctions(mGridStyle->mGridTemplateRows, mGridStyle->mGridAutoRows,
-                      aFrame->IsSubgrid(eLogicalAxisBlock)),
+                      aFrame->IsSubgrid(LogicalAxis::Block)),
         mReflowInput(aReflowInput),
         mRenderingContext(aRenderingContext),
         mFrame(aFrame),
@@ -3299,8 +3304,8 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput {
       mSkipSides = aFrame->PreReflowBlockLevelLogicalSkipSides();
       mBorderPadding.ApplySkipSides(mSkipSides);
     }
-    mCols.mIsMasonry = aFrame->IsMasonry(eLogicalAxisInline);
-    mRows.mIsMasonry = aFrame->IsMasonry(eLogicalAxisBlock);
+    mCols.mIsMasonry = aFrame->IsMasonry(LogicalAxis::Inline);
+    mRows.mIsMasonry = aFrame->IsMasonry(LogicalAxis::Block);
     MOZ_ASSERT(!(mCols.mIsMasonry && mRows.mIsMasonry),
                "can't have masonry layout in both axes");
   }
@@ -3463,7 +3468,7 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::Grid {
    * @param aFromIndex the zero-based index to start counting from
    * @param aLineNameList the explicit named lines
    * @param aSide the axis+edge we're resolving names for (e.g. if we're
-                  resolving a grid-row-start line, pass eLogicalSideBStart)
+                  resolving a grid-row-start line, pass LogicalSide::BStart)
    * @param aExplicitGridEnd the last line in the explicit grid
    * @param aStyle the StylePosition() for the grid container
    * @return a definite line (1-based), clamped to
@@ -3546,7 +3551,7 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::Grid {
     if (!mParentGrid) {
       return nullptr;
     }
-    bool isRows = aIsOrthogonal == (aAxis == eLogicalAxisInline);
+    bool isRows = aIsOrthogonal == (aAxis == LogicalAxis::Inline);
     return isRows ? mParentGrid->mRowNameMap : mParentGrid->mColNameMap;
   }
 
@@ -3684,38 +3689,56 @@ static Subgrid* SubgridComputeMarginBorderPadding(
   SizeComputationInput sz(subgridFrame, nullptr, cbWM, pmPercentageBasis);
   subgrid->mMarginBorderPadding =
       sz.ComputedLogicalMargin(cbWM) + sz.ComputedLogicalBorderPadding(cbWM);
+  if (aGridItem.mFrame == subgridFrame) {
+    return subgrid;
+  }
 
-  if (aGridItem.mFrame != subgridFrame) {
-    nsHTMLScrollFrame* scrollFrame =
-        do_QueryFrame(aGridItem.mFrame->GetScrollTargetFrame());
-    if (scrollFrame) {
-      MOZ_ASSERT(
-          sz.ComputedLogicalMargin(cbWM) == LogicalMargin(cbWM) &&
-              sz.ComputedLogicalBorder(cbWM) == LogicalMargin(cbWM),
-          "A scrolled inner frame should not have any margin or border!");
-
-      // Add the margin and border from the (outer) scroll frame.
-      SizeComputationInput szScrollFrame(aGridItem.mFrame, nullptr, cbWM,
-                                         pmPercentageBasis);
-      subgrid->mMarginBorderPadding +=
-          szScrollFrame.ComputedLogicalMargin(cbWM) +
-          szScrollFrame.ComputedLogicalBorder(cbWM);
-
-      nsMargin ssz = scrollFrame->IntrinsicScrollbarGutterSize();
+  bool scroller = false;
+  nsIFrame* outerFrame = [&]() -> nsIFrame* {
+    if (nsHTMLScrollFrame* scrollFrame =
+            do_QueryFrame(aGridItem.mFrame->GetScrollTargetFrame())) {
+      scroller = true;
+      return scrollFrame;
+    }
+    if (nsHTMLButtonControlFrame* f = do_QueryFrame(aGridItem.mFrame)) {
+      return f;
+    }
+    return nullptr;
+  }();
+
+  if (outerFrame) {
+    MOZ_ASSERT(sz.ComputedLogicalMargin(cbWM) == LogicalMargin(cbWM) &&
+                   sz.ComputedLogicalBorder(cbWM) == LogicalMargin(cbWM),
+               "A scrolled inner frame / button content frame "
+               "should not have any margin or border / padding!");
+
+    // Add the margin and border from the (outer) frame. Padding is factored-in
+    // for scrollers already (except for the scrollbar gutter), but not for
+    // button-content.
+    SizeComputationInput szOuterFrame(outerFrame, nullptr, cbWM,
+                                      pmPercentageBasis);
+    subgrid->mMarginBorderPadding += szOuterFrame.ComputedLogicalMargin(cbWM) +
+                                     szOuterFrame.ComputedLogicalBorder(cbWM);
+    if (scroller) {
+      nsMargin ssz = static_cast<nsHTMLScrollFrame*>(outerFrame)
+                         ->IntrinsicScrollbarGutterSize();
       subgrid->mMarginBorderPadding += LogicalMargin(cbWM, ssz);
+    } else {
+      subgrid->mMarginBorderPadding +=
+          szOuterFrame.ComputedLogicalPadding(cbWM);
     }
+  }
 
-    if (aGridItem.mFrame->IsFieldSetFrame()) {
-      const auto* f = static_cast<nsFieldSetFrame*>(aGridItem.mFrame);
-      const auto* inner = f->GetInner();
-      auto wm = inner->GetWritingMode();
-      LogicalPoint pos = inner->GetLogicalPosition(aGridItem.mFrame->GetSize());
-      // The legend is always on the BStart side and it inflates the fieldset's
-      // "border area" size.  The inner frame's b-start pos equals that size.
-      LogicalMargin offsets(wm, pos.B(wm), 0, 0, 0);
-      subgrid->mMarginBorderPadding += offsets.ConvertTo(cbWM, wm);
-    }
+  if (nsFieldSetFrame* f = do_QueryFrame(aGridItem.mFrame)) {
+    const auto* inner = f->GetInner();
+    auto wm = inner->GetWritingMode();
+    LogicalPoint pos = inner->GetLogicalPosition(aGridItem.mFrame->GetSize());
+    // The legend is always on the BStart side and it inflates the fieldset's
+    // "border area" size.  The inner frame's b-start pos equals that size.
+    LogicalMargin offsets(wm, pos.B(wm), 0, 0, 0);
+    subgrid->mMarginBorderPadding += offsets.ConvertTo(cbWM, wm);
   }
+
   return subgrid;
 }
 
@@ -3727,8 +3750,9 @@ static void CopyUsedTrackSizes(nsTArray<TrackSize>& aResult,
                                LogicalAxis aSubgridAxis) {
   MOZ_ASSERT(aSubgridFrame->ParentGridContainerForSubgrid() ==
              aUsedTrackSizesFrame);
-  aResult.SetLength(aSubgridAxis == eLogicalAxisInline ? aSubgrid->mGridColEnd
-                                                       : aSubgrid->mGridRowEnd);
+  aResult.SetLength(aSubgridAxis == LogicalAxis::Inline
+                        ? aSubgrid->mGridColEnd
+                        : aSubgrid->mGridRowEnd);
   auto parentAxis =
       aSubgrid->mIsOrthogonal ? GetOrthogonalAxis(aSubgridAxis) : aSubgridAxis;
   const auto& parentSizes = aUsedTrackSizes->mSizes[parentAxis];
@@ -3740,7 +3764,7 @@ static void CopyUsedTrackSizes(nsTArray<TrackSize>& aResult,
   const auto cbwm = aUsedTrackSizesFrame->GetWritingMode();
   const auto wm = aSubgridFrame->GetWritingMode();
   // Recompute the MBP to resolve percentages against the resolved track sizes.
-  if (parentAxis == eLogicalAxisInline) {
+  if (parentAxis == LogicalAxis::Inline) {
     // Find the subgrid's grid item frame in its parent grid container.  This
     // is usually the same as aSubgridFrame but it may also have a ScrollFrame,
     // FieldSetFrame etc.  We just loop until we see the first ancestor
@@ -3856,7 +3880,7 @@ void nsGridContainerFrame::UsedTrackSizes::ResolveSubgridTrackSizesForAxis(
   grid.mGridRowEnd = aSubgrid->mGridRowEnd;
   state.CalculateTrackSizesForAxis(aAxis, grid, aContentBoxSize,
                                    SizingConstraint::NoConstraint);
-  const auto& tracks = aAxis == eLogicalAxisInline ? state.mCols : state.mRows;
+  const auto& tracks = aAxis == LogicalAxis::Inline ? state.mCols : state.mRows;
   mSizes[aAxis].Assign(tracks.mSizes);
   mCanResolveLineRangeSize[aAxis] = tracks.mCanResolveLineRangeSize;
   MOZ_ASSERT(mCanResolveLineRangeSize[aAxis]);
@@ -3865,11 +3889,11 @@ void nsGridContainerFrame::UsedTrackSizes::ResolveSubgridTrackSizesForAxis(
 void nsGridContainerFrame::GridReflowInput::CalculateTrackSizesForAxis(
     LogicalAxis aAxis, const Grid& aGrid, nscoord aContentBoxSize,
     SizingConstraint aConstraint) {
-  auto& tracks = aAxis == eLogicalAxisInline ? mCols : mRows;
+  auto& tracks = aAxis == LogicalAxis::Inline ? mCols : mRows;
   const auto& sizingFunctions =
-      aAxis == eLogicalAxisInline ? mColFunctions : mRowFunctions;
-  const auto& gapStyle = aAxis == eLogicalAxisInline ? mGridStyle->mColumnGap
-                                                     : mGridStyle->mRowGap;
+      aAxis == LogicalAxis::Inline ? mColFunctions : mRowFunctions;
+  const auto& gapStyle = aAxis == LogicalAxis::Inline ? mGridStyle->mColumnGap
+                                                      : mGridStyle->mRowGap;
   if (tracks.mIsMasonry) {
     // See comment on nsGridContainerFrame::MasonryLayout().
     tracks.Initialize(sizingFunctions, gapStyle, 2, aContentBoxSize);
@@ -3877,7 +3901,7 @@ void nsGridContainerFrame::GridReflowInput::CalculateTrackSizesForAxis(
     return;
   }
   uint32_t gridEnd =
-      aAxis == eLogicalAxisInline ? aGrid.mGridColEnd : aGrid.mGridRowEnd;
+      aAxis == LogicalAxis::Inline ? aGrid.mGridColEnd : aGrid.mGridRowEnd;
   Maybe<TrackSizingFunctions> fallbackTrackSizing;
 
   bool useParentGaps = false;
@@ -3919,7 +3943,7 @@ void nsGridContainerFrame::GridReflowInput::CalculateTrackSizesForAxis(
         *this, mGridItems,
         fallbackTrackSizing ? *fallbackTrackSizing : sizingFunctions,
         aContentBoxSize,
-        aAxis == eLogicalAxisInline ? &GridArea::mCols : &GridArea::mRows,
+        aAxis == LogicalAxis::Inline ? &GridArea::mCols : &GridArea::mRows,
         aConstraint);
 
     if (hasSubgridItems &&
@@ -3976,9 +4000,9 @@ void nsGridContainerFrame::GridReflowInput::CalculateTrackSizesForAxis(
 void nsGridContainerFrame::GridReflowInput::CalculateTrackSizes(
     const Grid& aGrid, const LogicalSize& aContentBox,
     SizingConstraint aConstraint) {
-  CalculateTrackSizesForAxis(eLogicalAxisInline, aGrid, aContentBox.ISize(mWM),
+  CalculateTrackSizesForAxis(LogicalAxis::Inline, aGrid, aContentBox.ISize(mWM),
                              aConstraint);
-  CalculateTrackSizesForAxis(eLogicalAxisBlock, aGrid, aContentBox.BSize(mWM),
+  CalculateTrackSizesForAxis(LogicalAxis::Block, aGrid, aContentBox.BSize(mWM),
                              aConstraint);
 }
 
@@ -3999,7 +4023,7 @@ static void AlignJustifySelf(StyleAlignFlags aAlignment, LogicalAxis aAxis,
   // Set the position (aPos) for the requested alignment.
   if (offset != 0) {
     WritingMode wm = aRI.GetWritingMode();
-    nscoord& pos = aAxis == eLogicalAxisBlock ? aPos->B(wm) : aPos->I(wm);
+    nscoord& pos = aAxis == LogicalAxis::Block ? aPos->B(wm) : aPos->I(wm);
     pos += MOZ_LIKELY(aFlags & AlignJustifyFlags::SameSide) ? offset : -offset;
   }
 }
@@ -4016,7 +4040,7 @@ static void AlignSelf(const nsGridContainerFrame::GridItemInfo& aGridItem,
   aAlignSelf &= ~StyleAlignFlags::FLAG_BITS;
 
   WritingMode childWM = aRI.GetWritingMode();
-  if (aCBWM.ParallelAxisStartsOnSameSide(eLogicalAxisBlock, childWM)) {
+  if (aCBWM.ParallelAxisStartsOnSameSide(LogicalAxis::Block, childWM)) {
     flags |= AlignJustifyFlags::SameSide;
   }
 
@@ -4032,12 +4056,12 @@ static void AlignSelf(const nsGridContainerFrame::GridItemInfo& aGridItem,
   nscoord baselineAdjust = 0;
   if (aAlignSelf == StyleAlignFlags::BASELINE ||
       aAlignSelf == StyleAlignFlags::LAST_BASELINE) {
-    aAlignSelf = aGridItem.GetSelfBaseline(aAlignSelf, eLogicalAxisBlock,
+    aAlignSelf = aGridItem.GetSelfBaseline(aAlignSelf, LogicalAxis::Block,
                                            &baselineAdjust);
   }
 
   bool isOrthogonal = aCBWM.IsOrthogonalTo(childWM);
-  LogicalAxis axis = isOrthogonal ? eLogicalAxisInline : eLogicalAxisBlock;
+  LogicalAxis axis = isOrthogonal ? LogicalAxis::Inline : LogicalAxis::Block;
   AlignJustifySelf(aAlignSelf, axis, flags, baselineAdjust, aCBSize, aRI, aSize,
                    aPos);
 }
@@ -4054,7 +4078,7 @@ static void JustifySelf(const nsGridContainerFrame::GridItemInfo& aGridItem,
   aJustifySelf &= ~StyleAlignFlags::FLAG_BITS;
 
   WritingMode childWM = aRI.GetWritingMode();
-  if (aCBWM.ParallelAxisStartsOnSameSide(eLogicalAxisInline, childWM)) {
+  if (aCBWM.ParallelAxisStartsOnSameSide(LogicalAxis::Inline, childWM)) {
     flags |= AlignJustifyFlags::SameSide;
   }
 
@@ -4073,12 +4097,12 @@ static void JustifySelf(const nsGridContainerFrame::GridItemInfo& aGridItem,
         aCBWM.IsBidiLTR() ? StyleAlignFlags::END : StyleAlignFlags::START;
   } else if (aJustifySelf == StyleAlignFlags::BASELINE ||
              aJustifySelf == StyleAlignFlags::LAST_BASELINE) {
-    aJustifySelf = aGridItem.GetSelfBaseline(aJustifySelf, eLogicalAxisInline,
+    aJustifySelf = aGridItem.GetSelfBaseline(aJustifySelf, LogicalAxis::Inline,
                                              &baselineAdjust);
   }
 
   bool isOrthogonal = aCBWM.IsOrthogonalTo(childWM);
-  LogicalAxis axis = isOrthogonal ? eLogicalAxisBlock : eLogicalAxisInline;
+  LogicalAxis axis = isOrthogonal ? LogicalAxis::Block : LogicalAxis::Inline;
   AlignJustifySelf(aJustifySelf, axis, flags, baselineAdjust, aCBSize, aRI,
                    aSize, aPos);
 }
@@ -4245,8 +4269,8 @@ void nsGridContainerFrame::InitImplicitNamedAreas(
       AddImplicitNamedAreas(aTemplate.AsSubgrid()->line_names.AsSpan());
     }
   };
-  Add(aStyle->mGridTemplateColumns, IsSubgrid(eLogicalAxisInline));
-  Add(aStyle->mGridTemplateRows, IsSubgrid(eLogicalAxisBlock));
+  Add(aStyle->mGridTemplateColumns, IsSubgrid(LogicalAxis::Inline));
+  Add(aStyle->mGridTemplateRows, IsSubgrid(LogicalAxis::Block));
   if (areas && areas->count() == 0) {
     RemoveProperty(ImplicitNamedAreasProperty());
   }
@@ -4485,10 +4509,10 @@ nsGridContainerFrame::GridArea nsGridContainerFrame::Grid::PlaceDefinite(
   const nsStylePosition* itemStyle = aChild->StylePosition();
   return GridArea(
       ResolveLineRange(itemStyle->mGridColumnStart, itemStyle->mGridColumnEnd,
-                       aColLineNameMap, eLogicalAxisInline, mExplicitGridColEnd,
-                       aStyle),
+                       aColLineNameMap, LogicalAxis::Inline,
+                       mExplicitGridColEnd, aStyle),
       ResolveLineRange(itemStyle->mGridRowStart, itemStyle->mGridRowEnd,
-                       aRowLineNameMap, eLogicalAxisBlock, mExplicitGridRowEnd,
+                       aRowLineNameMap, LogicalAxis::Block, mExplicitGridRowEnd,
                        aStyle));
 }
 
@@ -4548,11 +4572,11 @@ nsGridContainerFrame::GridArea nsGridContainerFrame::Grid::PlaceAbsPos(
   int32_t gridRowStart = 1 - mExplicitGridOffsetRow;
   return GridArea(ResolveAbsPosLineRange(
                       itemStyle->mGridColumnStart, itemStyle->mGridColumnEnd,
-                      aColLineNameMap, eLogicalAxisInline, mExplicitGridColEnd,
+                      aColLineNameMap, LogicalAxis::Inline, mExplicitGridColEnd,
                       gridColStart, mGridColEnd, aStyle),
                   ResolveAbsPosLineRange(
                       itemStyle->mGridRowStart, itemStyle->mGridRowEnd,
-                      aRowLineNameMap, eLogicalAxisBlock, mExplicitGridRowEnd,
+                      aRowLineNameMap, LogicalAxis::Block, mExplicitGridRowEnd,
                       gridRowStart, mGridRowEnd, aStyle));
 }
 
@@ -4736,10 +4760,10 @@ void nsGridContainerFrame::Grid::SubgridPlaceGridItems(
   MOZ_ASSERT(aGridItem.mArea.IsDefinite() ||
                  aGridItem.mFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW),
              "the subgrid's lines should be resolved by now");
-  if (aGridItem.IsSubgrid(eLogicalAxisInline)) {
+  if (aGridItem.IsSubgrid(LogicalAxis::Inline)) {
     aParentState.mFrame->AddStateBits(NS_STATE_GRID_HAS_COL_SUBGRID_ITEM);
   }
-  if (aGridItem.IsSubgrid(eLogicalAxisBlock)) {
+  if (aGridItem.IsSubgrid(LogicalAxis::Block)) {
     aParentState.mFrame->AddStateBits(NS_STATE_GRID_HAS_ROW_SUBGRID_ITEM);
   }
   auto* childGrid = aGridItem.SubgridFrame();
@@ -4787,11 +4811,11 @@ void nsGridContainerFrame::Grid::SubgridPlaceGridItems(
   // computing them otherwise.
   RepeatTrackSizingInput repeatSizing(state.mWM);
   if (!childGrid->IsColSubgrid() && state.mColFunctions.mHasRepeatAuto) {
-    repeatSizing.InitFromStyle(eLogicalAxisInline, state.mWM,
+    repeatSizing.InitFromStyle(LogicalAxis::Inline, state.mWM,
                                state.mFrame->Style());
   }
   if (!childGrid->IsRowSubgrid() && state.mRowFunctions.mHasRepeatAuto) {
-    repeatSizing.InitFromStyle(eLogicalAxisBlock, state.mWM,
+    repeatSizing.InitFromStyle(LogicalAxis::Block, state.mWM,
                                state.mFrame->Style());
   }
 
@@ -4812,8 +4836,8 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
   if (aState.mFrame->HasSubgridItems() || aState.mFrame->IsSubgrid()) {
     if (auto* uts = aState.mFrame->GetUsedTrackSizes()) {
       uts->mCanResolveLineRangeSize = {false, false};
-      uts->mSizes[eLogicalAxisInline].ClearAndRetainStorage();
-      uts->mSizes[eLogicalAxisBlock].ClearAndRetainStorage();
+      uts->mSizes[LogicalAxis::Inline].ClearAndRetainStorage();
+      uts->mSizes[LogicalAxis::Block].ClearAndRetainStorage();
     }
   }
 
@@ -4847,11 +4871,11 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
     uint32_t extent = subgridRange->Extent();
     mExplicitGridColEnd = extent + 1;  // the grid is 1-based at this point
     parentLineNameMap =
-        ParentLineMapForAxis(subgrid->mIsOrthogonal, eLogicalAxisInline);
+        ParentLineMapForAxis(subgrid->mIsOrthogonal, LogicalAxis::Inline);
     auto parentWM =
         aState.mFrame->ParentGridContainerForSubgrid()->GetWritingMode();
     subgridAxisIsSameDirection =
-        aState.mWM.ParallelAxisStartsOnSameSide(eLogicalAxisInline, parentWM);
+        aState.mWM.ParallelAxisStartsOnSameSide(LogicalAxis::Inline, parentWM);
   }
   mGridColEnd = mExplicitGridColEnd;
   LineNameMap colLineNameMap(gridStyle, mAreas, aState.mColFunctions,
@@ -4882,11 +4906,11 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
     uint32_t extent = subgridRange->Extent();
     mExplicitGridRowEnd = extent + 1;  // the grid is 1-based at this point
     parentLineNameMap =
-        ParentLineMapForAxis(subgrid->mIsOrthogonal, eLogicalAxisBlock);
+        ParentLineMapForAxis(subgrid->mIsOrthogonal, LogicalAxis::Block);
     auto parentWM =
         aState.mFrame->ParentGridContainerForSubgrid()->GetWritingMode();
     subgridAxisIsSameDirection =
-        aState.mWM.ParallelAxisStartsOnSameSide(eLogicalAxisBlock, parentWM);
+        aState.mWM.ParallelAxisStartsOnSameSide(LogicalAxis::Block, parentWM);
   }
   mGridRowEnd = mExplicitGridRowEnd;
   LineNameMap rowLineNameMap(gridStyle, mAreas, aState.mRowFunctions,
@@ -4900,16 +4924,16 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
     if (isSubgridOrItemInSubgrid) {
       const auto& area = aItem.mArea;
       if (area.mCols.mStart == 0) {
-        aItem.mState[eLogicalAxisInline] |= ItemState::eStartEdge;
+        aItem.mState[LogicalAxis::Inline] |= ItemState::eStartEdge;
       }
       if (area.mCols.mEnd == mGridColEnd) {
-        aItem.mState[eLogicalAxisInline] |= ItemState::eEndEdge;
+        aItem.mState[LogicalAxis::Inline] |= ItemState::eEndEdge;
       }
       if (area.mRows.mStart == 0) {
-        aItem.mState[eLogicalAxisBlock] |= ItemState::eStartEdge;
+        aItem.mState[LogicalAxis::Block] |= ItemState::eStartEdge;
       }
       if (area.mRows.mEnd == mGridRowEnd) {
-        aItem.mState[eLogicalAxisBlock] |= ItemState::eEndEdge;
+        aItem.mState[LogicalAxis::Block] |= ItemState::eEndEdge;
       }
     }
   };
@@ -4945,8 +4969,8 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
   aState.mRowFunctions.mExplicitGridOffset = mExplicitGridOffsetRow;
   const int32_t offsetToColZero = int32_t(mExplicitGridOffsetCol) - 1;
   const int32_t offsetToRowZero = int32_t(mExplicitGridOffsetRow) - 1;
-  const bool isRowMasonry = aState.mFrame->IsMasonry(eLogicalAxisBlock);
-  const bool isColMasonry = aState.mFrame->IsMasonry(eLogicalAxisInline);
+  const bool isRowMasonry = aState.mFrame->IsMasonry(LogicalAxis::Block);
+  const bool isColMasonry = aState.mFrame->IsMasonry(LogicalAxis::Inline);
   const bool isMasonry = isColMasonry || isRowMasonry;
   mGridColEnd += offsetToColZero;
   mGridRowEnd += offsetToRowZero;
@@ -5100,7 +5124,7 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
   // Force all items into the 1st/2nd track and have span 1 in the masonry axis.
   // (See comment on nsGridContainerFrame::MasonryLayout().)
   if (isMasonry) {
-    auto masonryAxis = isRowMasonry ? eLogicalAxisBlock : eLogicalAxisInline;
+    auto masonryAxis = isRowMasonry ? LogicalAxis::Block : LogicalAxis::Inline;
     aState.mIter.Reset();
     for (; !aState.mIter.AtEnd(); aState.mIter.Next()) {
       auto& item = aState.mGridItems[aState.mIter.ItemIndex()];
@@ -5168,16 +5192,16 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
 
       // An abs.pos. subgrid with placement auto/1 or -1/auto technically
       // doesn't span any parent tracks.  Inhibit subgridding in this case.
-      if (info->IsSubgrid(eLogicalAxisInline)) {
+      if (info->IsSubgrid(LogicalAxis::Inline)) {
         if (info->mArea.mCols.mStart == zeroOffsetGridColEnd.SavedValue() ||
             info->mArea.mCols.mEnd == 0) {
-          info->InhibitSubgrid(aState.mFrame, eLogicalAxisInline);
+          info->InhibitSubgrid(aState.mFrame, LogicalAxis::Inline);
         }
       }
-      if (info->IsSubgrid(eLogicalAxisBlock)) {
+      if (info->IsSubgrid(LogicalAxis::Block)) {
         if (info->mArea.mRows.mStart == zeroOffsetGridRowEnd.SavedValue() ||
             info->mArea.mRows.mEnd == 0) {
-          info->InhibitSubgrid(aState.mFrame, eLogicalAxisBlock);
+          info->InhibitSubgrid(aState.mFrame, LogicalAxis::Block);
         }
       }
 
@@ -5219,18 +5243,18 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
     // Adjust the line numbers in the grid areas.
     for (auto& item : aState.mGridItems) {
       if (numEmptyCols) {
-        item.AdjustForRemovedTracks(eLogicalAxisInline, *colAdjust);
+        item.AdjustForRemovedTracks(LogicalAxis::Inline, *colAdjust);
       }
       if (numEmptyRows) {
-        item.AdjustForRemovedTracks(eLogicalAxisBlock, *rowAdjust);
+        item.AdjustForRemovedTracks(LogicalAxis::Block, *rowAdjust);
       }
     }
     for (auto& item : aState.mAbsPosItems) {
       if (numEmptyCols) {
-        item.AdjustForRemovedTracks(eLogicalAxisInline, *colAdjust);
+        item.AdjustForRemovedTracks(LogicalAxis::Inline, *colAdjust);
       }
       if (numEmptyRows) {
-        item.AdjustForRemovedTracks(eLogicalAxisBlock, *rowAdjust);
+        item.AdjustForRemovedTracks(LogicalAxis::Block, *rowAdjust);
       }
     }
     // Adjust the grid size.
@@ -5258,11 +5282,11 @@ void nsGridContainerFrame::Grid::PlaceGridItems(
 
       LineRange columnLines =
           ResolveLineRange(lineStartAndEnd, lineStartAndEnd, colLineNameMap,
-                           eLogicalAxisInline, mExplicitGridColEnd, gridStyle);
+                           LogicalAxis::Inline, mExplicitGridColEnd, gridStyle);
 
       LineRange rowLines =
           ResolveLineRange(lineStartAndEnd, lineStartAndEnd, rowLineNameMap,
-                           eLogicalAxisBlock, mExplicitGridRowEnd, gridStyle);
+                           LogicalAxis::Block, mExplicitGridRowEnd, gridStyle);
 
       // Put the resolved line indices back into the area structure.
       areaInfo.columns.start = columnLines.mStart + mExplicitGridOffsetCol;
@@ -5322,7 +5346,7 @@ static nscoord MeasuringReflow(nsIFrame* aChild,
   ComputeSizeFlags csFlags = ComputeSizeFlag::IsGridMeasuringReflow;
   // Shrink-wrap grid items that will be aligned (rather than stretched) in
   // their own inline axis.
-  if (!parent->GridItemShouldStretch(aChild, eLogicalAxisInline)) {
+  if (!parent->GridItemShouldStretch(aChild, LogicalAxis::Inline)) {
     csFlags += ComputeSizeFlag::ShrinkWrap;
   }
   if (aAvailableSize.ISize(wm) == INFINITE_ISIZE_COORD) {
@@ -5434,7 +5458,7 @@ static void PostReflowStretchChild(
   }
   ReflowInput ri(pc, aReflowInput, aChild, aAvailableSize, Some(aCBSize), {},
                  {}, csFlags);
-  if (aChildAxis == eLogicalAxisBlock) {
+  if (aChildAxis == LogicalAxis::Block) {
     ri.SetComputedBSize(ri.ApplyMinMaxBSize(aNewContentBoxSize));
   } else {
     ri.SetComputedISize(ri.ApplyMinMaxISize(aNewContentBoxSize));
@@ -5542,18 +5566,18 @@ static nscoord ContentContribution(
       auto subgridAxis = aCBWM.IsOrthogonalTo(subgridFrame->GetWritingMode())
                              ? GetOrthogonalAxis(aAxis)
                              : aAxis;
-      auto& gapStyle = subgridAxis == eLogicalAxisBlock
+      auto& gapStyle = subgridAxis == LogicalAxis::Block
                            ? subgridFrame->StylePosition()->mRowGap
                            : subgridFrame->StylePosition()->mColumnGap;
       if (!gapStyle.IsNormal()) {
-        auto subgridExtent = subgridAxis == eLogicalAxisBlock
+        auto subgridExtent = subgridAxis == LogicalAxis::Block
                                  ? subgrid->mGridRowEnd
                                  : subgrid->mGridColEnd;
         if (subgridExtent > 1) {
           nscoord subgridGap =
               nsLayoutUtils::ResolveGapToLength(gapStyle, NS_UNCONSTRAINEDSIZE);
           auto& tracks =
-              aAxis == eLogicalAxisBlock ? aState.mRows : aState.mCols;
+              aAxis == LogicalAxis::Block ? aState.mRows : aState.mCols;
           auto gapDelta = subgridGap - tracks.mGridGap;
           if (!itemEdgeBits) {
             extraMargin += gapDelta;
@@ -5572,7 +5596,7 @@ static nscoord ContentContribution(
   auto childWM = child->GetWritingMode();
   const bool isOrthogonal = childWM.IsOrthogonalTo(aCBWM);
   auto childAxis = isOrthogonal ? GetOrthogonalAxis(aAxis) : aAxis;
-  if (size == NS_INTRINSIC_ISIZE_UNKNOWN && childAxis == eLogicalAxisBlock) {
+  if (size == NS_INTRINSIC_ISIZE_UNKNOWN && childAxis == LogicalAxis::Block) {
     // We need to reflow the child to find its BSize contribution.
     // XXX this will give mostly correct results for now (until bug 1174569).
     nscoord availISize = INFINITE_ISIZE_COORD;
@@ -5595,8 +5619,8 @@ static nscoord ContentContribution(
       }
       // The grid-item's inline-axis as expressed in the subgrid's WM.
       auto subgridAxis = childWM.IsOrthogonalTo(subgridFrame->GetWritingMode())
-                             ? eLogicalAxisBlock
-                             : eLogicalAxisInline;
+                             ? LogicalAxis::Block
+                             : LogicalAxis::Inline;
       uts->ResolveTrackSizesForAxis(subgridFrame, subgridAxis, *aRC);
       if (uts->mCanResolveLineRangeSize[subgridAxis]) {
         auto* subgrid =
@@ -5642,7 +5666,7 @@ static nscoord ContentContribution(
         }
       }
     }
-    if (isOrthogonal == (aAxis == eLogicalAxisInline)) {
+    if (isOrthogonal == (aAxis == LogicalAxis::Inline)) {
       bMinSizeClamp = aMinSizeClamp;
     } else {
       iMinSizeClamp = aMinSizeClamp;
@@ -5739,7 +5763,8 @@ static nscoord MinSize(const GridItemInfo& aGridItem,
   StyleSize sizeStyle =
       axis == eAxisHorizontal ? stylePos->mWidth : stylePos->mHeight;
 
-  auto ourInlineAxis = child->GetWritingMode().PhysicalAxis(eLogicalAxisInline);
+  auto ourInlineAxis =
+      child->GetWritingMode().PhysicalAxis(LogicalAxis::Inline);
   // max-content and min-content should behave as initial value in block axis.
   // FIXME: Bug 567039: moz-fit-content and -moz-available are not supported
   // for block size dimension on sizing properties (e.g. height), so we
@@ -6006,7 +6031,7 @@ void nsGridContainerFrame::Tracks::InitializeItemBaselines(
     const auto childWM = child->GetWritingMode();
 
     const bool isOrthogonal = containerWM.IsOrthogonalTo(childWM);
-    const bool isInlineAxis = mAxis == eLogicalAxisInline;  // i.e. columns
+    const bool isInlineAxis = mAxis == LogicalAxis::Inline;  // i.e. columns
 
     // XXX update the line below to include orthogonal grid/table boxes
     // XXX since they have baselines in both dimensions. And flexbox with
@@ -6281,7 +6306,7 @@ void nsGridContainerFrame::Tracks::InitializeItemBaselinesInMasonryAxis(
     auto state = ItemState(0);
     auto childWM = child->GetWritingMode();
     const bool isOrthogonal = wm.IsOrthogonalTo(childWM);
-    const bool isInlineAxis = mAxis == eLogicalAxisInline;  // i.e. columns
+    const bool isInlineAxis = mAxis == LogicalAxis::Inline;  // i.e. columns
     // XXX update the line below to include orthogonal grid/table boxes
     // XXX since they have baselines in both dimensions. And flexbox with
     // XXX reversed main/cross axis?
@@ -6449,10 +6474,10 @@ void nsGridContainerFrame::Tracks::AlignBaselineSubtree(
   const bool isFirstBaseline = state & ItemState::eFirstBaseline;
   if (isFirstBaseline) {
     baselineTrack =
-        mAxis == eLogicalAxisBlock ? area.mRows.mStart : area.mCols.mStart;
+        mAxis == LogicalAxis::Block ? area.mRows.mStart : area.mCols.mStart;
   } else {
     baselineTrack =
-        (mAxis == eLogicalAxisBlock ? area.mRows.mEnd : area.mCols.mEnd) - 1;
+        (mAxis == LogicalAxis::Block ? area.mRows.mEnd : area.mCols.mEnd) - 1;
   }
   const TrackSize& sz = mSizes[baselineTrack];
   auto baselineGroup = isFirstBaseline ? BaselineSharingGroup::First
@@ -6855,7 +6880,7 @@ float nsGridContainerFrame::Tracks::FindUsedFlexFraction(
       nscoord spaceToFill = ContentContribution(item, aState, rc, wm, mAxis, pb,
                                                 IntrinsicISizeType::PrefISize);
       const LineRange& range =
-          mAxis == eLogicalAxisInline ? item.mArea.mCols : item.mArea.mRows;
+          mAxis == LogicalAxis::Inline ? item.mArea.mCols : item.mArea.mRows;
       MOZ_ASSERT(range.Extent() >= 1);
       const auto spannedGaps = range.Extent() - 1;
       if (spannedGaps > 0) {
@@ -6898,10 +6923,10 @@ void nsGridContainerFrame::Tracks::StretchFlexibleTracks(
   nscoord maxSize = NS_UNCONSTRAINEDSIZE;
   if (aState.mReflowInput) {
     auto* ri = aState.mReflowInput;
-    minSize = mAxis == eLogicalAxisBlock ? ri->ComputedMinBSize()
-                                         : ri->ComputedMinISize();
-    maxSize = mAxis == eLogicalAxisBlock ? ri->ComputedMaxBSize()
-                                         : ri->ComputedMaxISize();
+    minSize = mAxis == LogicalAxis::Block ? ri->ComputedMinBSize()
+                                          : ri->ComputedMinISize();
+    maxSize = mAxis == LogicalAxis::Block ? ri->ComputedMaxBSize()
+                                          : ri->ComputedMaxISize();
   }
   Maybe<CopyableAutoTArray<TrackSize, 32>> origSizes;
   bool applyMinMax = (minSize != 0 || maxSize != NS_UNCONSTRAINEDSIZE) &&
@@ -6958,7 +6983,7 @@ void nsGridContainerFrame::Tracks::StretchFlexibleTracks(
 void nsGridContainerFrame::Tracks::AlignJustifyContent(
     const nsStylePosition* aStyle, StyleContentDistribution aAligmentStyleValue,
     WritingMode aWM, nscoord aContentBoxSize, bool aIsSubgriddedAxis) {
-  const bool isAlign = mAxis == eLogicalAxisBlock;
+  const bool isAlign = mAxis == LogicalAxis::Block;
   // Align-/justify-content doesn't apply in a subgridded axis.
   // Gap properties do apply though so we need to stretch/position the tracks
   // to center-align the gaps with the parent's gaps.
@@ -7223,25 +7248,25 @@ LogicalSize nsGridContainerFrame::GridReflowInput::PercentageBasisFor(
     if (auto* uts = subgridFrame->GetUsedTrackSizes()) {
       auto subgridWM = subgridFrame->GetWritingMode();
       LogicalSize cbSize(subgridWM, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
-      if (!subgridFrame->IsSubgrid(eLogicalAxisInline) &&
-          uts->mCanResolveLineRangeSize[eLogicalAxisInline]) {
+      if (!subgridFrame->IsSubgrid(LogicalAxis::Inline) &&
+          uts->mCanResolveLineRangeSize[LogicalAxis::Inline]) {
         // NOTE: At this point aGridItem.mArea is in this->mFrame coordinates
         // and thus may have been transposed.  The range values in a non-
         // subgridded axis still has its original values in subgridFrame's
         // coordinates though.
-        auto rangeAxis = subgridWM.IsOrthogonalTo(mWM) ? eLogicalAxisBlock
-                                                       : eLogicalAxisInline;
+        auto rangeAxis = subgridWM.IsOrthogonalTo(mWM) ? LogicalAxis::Block
+                                                       : LogicalAxis::Inline;
         const auto& range = aGridItem.mArea.LineRangeForAxis(rangeAxis);
         cbSize.ISize(subgridWM) =
-            range.ToLength(uts->mSizes[eLogicalAxisInline]);
+            range.ToLength(uts->mSizes[LogicalAxis::Inline]);
       }
-      if (!subgridFrame->IsSubgrid(eLogicalAxisBlock) &&
-          uts->mCanResolveLineRangeSize[eLogicalAxisBlock]) {
-        auto rangeAxis = subgridWM.IsOrthogonalTo(mWM) ? eLogicalAxisInline
-                                                       : eLogicalAxisBlock;
+      if (!subgridFrame->IsSubgrid(LogicalAxis::Block) &&
+          uts->mCanResolveLineRangeSize[LogicalAxis::Block]) {
+        auto rangeAxis = subgridWM.IsOrthogonalTo(mWM) ? LogicalAxis::Inline
+                                                       : LogicalAxis::Block;
         const auto& range = aGridItem.mArea.LineRangeForAxis(rangeAxis);
         cbSize.BSize(subgridWM) =
-            range.ToLength(uts->mSizes[eLogicalAxisBlock]);
+            range.ToLength(uts->mSizes[LogicalAxis::Block]);
       }
       return cbSize.ConvertTo(wm, subgridWM);
     }
@@ -7249,7 +7274,7 @@ LogicalSize nsGridContainerFrame::GridReflowInput::PercentageBasisFor(
     return LogicalSize(wm, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
 
-  if (aAxis == eLogicalAxisInline || !mCols.mCanResolveLineRangeSize) {
+  if (aAxis == LogicalAxis::Inline || !mCols.mCanResolveLineRangeSize) {
     return LogicalSize(wm, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   // Note: for now, we only resolve transferred percentages to row sizing.
@@ -7428,7 +7453,7 @@ void nsGridContainerFrame::GridReflowInput::AlignJustifyTracksInMasonryAxis(
                 ContainingBlockFor(item->mArea).Size(wm).ConvertTo(childWM, wm);
             LogicalSize availableSize = cb;
             cb.Size(masonryChildAxis, childWM) = alignmentContainerSize;
-            availableSize.Size(eLogicalAxisBlock, childWM) =
+            availableSize.Size(LogicalAxis::Block, childWM) =
                 NS_UNCONSTRAINEDSIZE;
             const auto& bp = child->GetLogicalUsedBorderAndPadding(childWM);
             newSize -= bp.StartEnd(masonryChildAxis, childWM);
@@ -7626,9 +7651,9 @@ void nsGridContainerFrame::ReflowInFlowChild(
         aChild->RemoveProperty(aProp);
       }
     };
-    SetProp(eLogicalAxisBlock,
+    SetProp(LogicalAxis::Block,
             isOrthogonal ? IBaselinePadProperty() : BBaselinePadProperty());
-    SetProp(eLogicalAxisInline,
+    SetProp(LogicalAxis::Inline,
             isOrthogonal ? BBaselinePadProperty() : IBaselinePadProperty());
   } else {
     // By convention, for frames that perform CSS Box Alignment, we position
@@ -7654,9 +7679,9 @@ void nsGridContainerFrame::ReflowInFlowChild(
   ComputeSizeFlags csFlags;
   if (aGridItemInfo) {
     const auto childIAxisInWM =
-        isOrthogonal ? eLogicalAxisBlock : eLogicalAxisInline;
+        isOrthogonal ? LogicalAxis::Block : LogicalAxis::Inline;
     // Clamp during reflow if we're stretching in that axis.
-    if (GridItemShouldStretch(aChild, eLogicalAxisInline)) {
+    if (GridItemShouldStretch(aChild, LogicalAxis::Inline)) {
       if (aGridItemInfo->mState[childIAxisInWM] &
           ItemState::eClampMarginBoxMinSize) {
         csFlags += ComputeSizeFlag::IClampMarginBoxMinSize;
@@ -7666,7 +7691,7 @@ void nsGridContainerFrame::ReflowInFlowChild(
     }
 
     const auto childBAxisInWM = GetOrthogonalAxis(childIAxisInWM);
-    if (GridItemShouldStretch(aChild, eLogicalAxisBlock) &&
+    if (GridItemShouldStretch(aChild, LogicalAxis::Block) &&
         aGridItemInfo->mState[childBAxisInWM] &
             ItemState::eClampMarginBoxMinSize) {
       csFlags += ComputeSizeFlag::BClampMarginBoxMinSize;
@@ -7702,7 +7727,7 @@ void nsGridContainerFrame::ReflowInFlowChild(
   // nsBlockFrame::ComputeFinalSize the size.
   if (isConstrainedBSize && !wm.IsOrthogonalTo(childWM)) {
     const bool stretch = childRI.mStylePosition->BSize(childWM).IsAuto() &&
-                         GridItemShouldStretch(aChild, eLogicalAxisBlock);
+                         GridItemShouldStretch(aChild, LogicalAxis::Block);
     if (stretch) {
       aChild->SetProperty(FragStretchBSizeProperty(), *aStretchBSize);
     } else {
@@ -7750,7 +7775,7 @@ void nsGridContainerFrame::ReflowInFlowChild(
                      ? StyleAlignFlags::SELF_START
                      : StyleAlignFlags::SELF_END};
       }
-      if (aAxis == eLogicalAxisBlock) {
+      if (aAxis == LogicalAxis::Block) {
         AlignSelf(*aGridItemInfo, align, aCBSize, wm, childRI, size, flags,
                   &childPos);
       } else {
@@ -7759,10 +7784,10 @@ void nsGridContainerFrame::ReflowInFlowChild(
       }
     };
     if (aStatus.IsComplete()) {
-      applyItemSelfAlignment(eLogicalAxisBlock,
+      applyItemSelfAlignment(LogicalAxis::Block,
                              cb.BSize(wm) - consumedGridAreaBSize);
     }
-    applyItemSelfAlignment(eLogicalAxisInline, cb.ISize(wm));
+    applyItemSelfAlignment(LogicalAxis::Inline, cb.ISize(wm));
   }  // else, nsAbsoluteContainingBlock.cpp will handle align/justify-self.
 
   FinishReflowChild(aChild, pc, childSize, &childRI, childWM, childPos,
@@ -8006,7 +8031,7 @@ nscoord nsGridContainerFrame::ReflowRowsInFragmentainer(
   const auto rowCount = aState.mRows.mSizes.Length();
   nscoord masonryAxisGap;
   const auto wm = aState.mWM;
-  const bool isColMasonry = IsMasonry(eLogicalAxisInline);
+  const bool isColMasonry = IsMasonry(LogicalAxis::Inline);
   if (isColMasonry) {
     for (auto& sz : aState.mCols.mSizes) {
       sz.mPosition = 0;
@@ -8174,15 +8199,15 @@ nscoord nsGridContainerFrame::ReflowRowsInFragmentainer(
     }
     if (isColMasonry) {
       auto childWM = child->GetWritingMode();
-      auto childAxis =
-          !childWM.IsOrthogonalTo(wm) ? eLogicalAxisInline : eLogicalAxisBlock;
+      auto childAxis = !childWM.IsOrthogonalTo(wm) ? LogicalAxis::Inline
+                                                   : LogicalAxis::Block;
       auto normalPos = child->GetLogicalNormalPosition(wm, aContainerSize);
       auto sz =
-          childAxis == eLogicalAxisBlock ? child->BSize() : child->ISize();
-      auto pos = normalPos.Pos(eLogicalAxisInline, wm) + sz +
+          childAxis == LogicalAxis::Block ? child->BSize() : child->ISize();
+      auto pos = normalPos.Pos(LogicalAxis::Inline, wm) + sz +
                  child->GetLogicalUsedMargin(childWM).End(childAxis, childWM);
       masonryAxisPos.ref()[row] =
-          pos + masonryAxisGap - aContentArea.Start(eLogicalAxisInline, wm);
+          pos + masonryAxisGap - aContentArea.Start(LogicalAxis::Inline, wm);
     }
   }
 
@@ -8281,7 +8306,7 @@ nscoord nsGridContainerFrame::MasonryLayout(GridReflowInput& aState,
   aState.mIter.Reset(CSSOrderAwareFrameIterator::ChildFilter::IncludeAll);
   size_t absposIndex = 0;
   const LogicalAxis masonryAxis =
-      IsMasonry(eLogicalAxisBlock) ? eLogicalAxisBlock : eLogicalAxisInline;
+      IsMasonry(LogicalAxis::Block) ? LogicalAxis::Block : LogicalAxis::Inline;
   const auto wm = aState.mWM;
   for (; !aState.mIter.AtEnd(); aState.mIter.Next()) {
     nsIFrame* child = *aState.mIter;
@@ -8323,7 +8348,7 @@ nscoord nsGridContainerFrame::MasonryLayout(GridReflowInput& aState,
   const auto masonryAutoFlow = aState.mGridStyle->mMasonryAutoFlow;
   const bool definiteFirst =
       masonryAutoFlow.order == StyleMasonryItemOrder::DefiniteFirst;
-  if (masonryAxis == eLogicalAxisBlock) {
+  if (masonryAxis == LogicalAxis::Block) {
     std::stable_sort(sortedItems.begin(), sortedItems.end(),
                      definiteFirst ? GridItemInfo::RowMasonryDefiniteFirst
                                    : GridItemInfo::RowMasonryOrdered);
@@ -8366,8 +8391,8 @@ nscoord nsGridContainerFrame::MasonryLayout(GridReflowInput& aState,
   lastItems.SetLength(gridAxisTrackCount);
   PodZero(lastItems.Elements(), gridAxisTrackCount);
   const nscoord gap = nsLayoutUtils::ResolveGapToLength(
-      masonryAxis == eLogicalAxisBlock ? aState.mGridStyle->mRowGap
-                                       : aState.mGridStyle->mColumnGap,
+      masonryAxis == LogicalAxis::Block ? aState.mGridStyle->mRowGap
+                                        : aState.mGridStyle->mColumnGap,
       masonryTracks.mContentBoxSize);
   masonryTracks.mGridGap = gap;
   uint32_t cursor = 0;
@@ -8495,7 +8520,7 @@ nscoord nsGridContainerFrame::MasonryLayout(GridReflowInput& aState,
     auto childAxis = !childWM.IsOrthogonalTo(wm) ? masonryAxis : gridAxis;
     auto normalPos = aChild->GetLogicalNormalPosition(wm, aContainerSize);
     auto sz =
-        childAxis == eLogicalAxisBlock ? aChild->BSize() : aChild->ISize();
+        childAxis == LogicalAxis::Block ? aChild->BSize() : aChild->ISize();
     return containerToMasonryBoxOffset + normalPos.Pos(masonryAxis, wm) + sz +
            aChild->GetLogicalUsedMargin(childWM).End(childAxis, childWM);
   };
@@ -8668,7 +8693,7 @@ nscoord nsGridContainerFrame::MasonryLayout(GridReflowInput& aState,
             consumeAllSpace ? toFragmentainerEnd : offsetToMarginBoxEnd(child);
       } else {
         LogicalSize percentBasis(
-            aState.PercentageBasisFor(eLogicalAxisInline, *item));
+            aState.PercentageBasisFor(LogicalAxis::Inline, *item));
         IntrinsicISizeType type = aConstraint == SizingConstraint::MaxContent
                                       ? IntrinsicISizeType::PrefISize
                                       : IntrinsicISizeType::MinISize;
@@ -8775,19 +8800,19 @@ nscoord nsGridContainerFrame::ReflowChildren(GridReflowInput& aState,
   // so we let ReflowInFragmentainer() deal with grid-axis fragmentation
   // in the else-clause below.
   if (IsMasonry() &&
-      !(IsMasonry(eLogicalAxisInline) && fragmentainer.isSome())) {
+      !(IsMasonry(LogicalAxis::Inline) && fragmentainer.isSome())) {
     aState.mInFragmentainer = fragmentainer.isSome();
     nscoord sz = MasonryLayout(
         aState, aContentArea, SizingConstraint::NoConstraint, aDesiredSize,
         aStatus, fragmentainer.ptrOr(nullptr), aContainerSize);
-    if (IsMasonry(eLogicalAxisBlock)) {
+    if (IsMasonry(LogicalAxis::Block)) {
       bSize = aState.mReflowInput->ComputedBSize();
       if (bSize == NS_UNCONSTRAINEDSIZE) {
         bSize = aState.mReflowInput->ApplyMinMaxBSize(sz);
       }
     }
   } else if (MOZ_UNLIKELY(fragmentainer.isSome())) {
-    if (IsMasonry(eLogicalAxisInline) && !GetPrevInFlow()) {
+    if (IsMasonry(LogicalAxis::Inline) && !GetPrevInFlow()) {
       // First we do an unconstrained reflow to resolve the item placement
       // which is then kept as-is in the constrained reflow below.
       MasonryLayout(aState, aContentArea, SizingConstraint::NoConstraint,
@@ -8804,10 +8829,12 @@ nscoord nsGridContainerFrame::ReflowChildren(GridReflowInput& aState,
       if (!child->IsPlaceholderFrame()) {
         info = &aState.mGridItems[aState.mIter.ItemIndex()];
       }
+      nsReflowStatus childStatus;
       ReflowInFlowChild(child, info, aContainerSize, Nothing(), nullptr, aState,
-                        aContentArea, aDesiredSize, aStatus);
-      MOZ_ASSERT(aStatus.IsComplete(),
+                        aContentArea, aDesiredSize, childStatus);
+      MOZ_ASSERT(childStatus.IsComplete(),
                  "child should be complete in unconstrained reflow");
+      aStatus.MergeCompletionStatusFrom(childStatus);
     }
   }
 
@@ -8868,7 +8895,6 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
 
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsGridContainerFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   if (IsFrameTreeTooDeep(aReflowInput, aDesiredSize, aStatus)) {
@@ -8952,11 +8978,11 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
     if (containBSize) {
       bSize = *containBSize;
     } else {
-      if (IsMasonry(eLogicalAxisBlock)) {
+      if (IsMasonry(LogicalAxis::Block)) {
         bSize = computedBSize;
       } else {
         const auto& rowSizes = gridReflowInput.mRows.mSizes;
-        if (MOZ_LIKELY(!IsSubgrid(eLogicalAxisBlock))) {
+        if (MOZ_LIKELY(!IsSubgrid(LogicalAxis::Block))) {
           // Note: we can't use GridLineEdge here since we haven't calculated
           // the rows' mPosition yet (happens in AlignJustifyContent below).
           for (const auto& sz : rowSizes) {
@@ -9025,7 +9051,7 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
     }
     // Save the final row sizes for use by subgrids, if needed.
     if (HasSubgridItems() || IsSubgrid()) {
-      StoreUsedTrackSizes(eLogicalAxisBlock, rowSizes);
+      StoreUsedTrackSizes(LogicalAxis::Block, rowSizes);
     }
   }
 
@@ -9122,8 +9148,8 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
   }
 
   // TODO: fix align-tracks alignment in fragments
-  if ((IsMasonry(eLogicalAxisBlock) && !prevInFlow) ||
-      IsMasonry(eLogicalAxisInline)) {
+  if ((IsMasonry(LogicalAxis::Block) && !prevInFlow) ||
+      IsMasonry(LogicalAxis::Inline)) {
     gridReflowInput.AlignJustifyTracksInMasonryAxis(
         contentArea.Size(wm), aDesiredSize.PhysicalSize());
   }
@@ -9221,7 +9247,7 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
     // the ComputedGridTrackInfo and related properties
 
     const auto* subgrid = GetProperty(Subgrid::Prop());
-    const auto* subgridColRange = subgrid && IsSubgrid(eLogicalAxisInline)
+    const auto* subgridColRange = subgrid && IsSubgrid(LogicalAxis::Inline)
                                       ? &subgrid->SubgridCols()
                                       : nullptr;
 
@@ -9252,7 +9278,7 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
     // taken by rvalue, but computing the size first prevents any changes in the
     // argument types of the constructor from breaking this.
     const uint32_t numColExplicitTracks =
-        IsSubgrid(eLogicalAxisInline)
+        IsSubgrid(LogicalAxis::Inline)
             ? colTrackSizes.Length()
             : gridReflowInput.mColFunctions.NumExplicitTracks();
     ComputedGridTrackInfo* colInfo = new ComputedGridTrackInfo(
@@ -9261,10 +9287,10 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
         std::move(colTrackStates), std::move(colRemovedRepeatTracks),
         gridReflowInput.mColFunctions.mRepeatAutoStart,
         colLineNameMap.GetResolvedLineNamesForComputedGridTrackInfo(),
-        IsSubgrid(eLogicalAxisInline), IsMasonry(eLogicalAxisInline));
+        IsSubgrid(LogicalAxis::Inline), IsMasonry(LogicalAxis::Inline));
     SetProperty(GridColTrackInfo(), colInfo);
 
-    const auto* subgridRowRange = subgrid && IsSubgrid(eLogicalAxisBlock)
+    const auto* subgridRowRange = subgrid && IsSubgrid(LogicalAxis::Block)
                                       ? &subgrid->SubgridRows()
                                       : nullptr;
     LineNameMap rowLineNameMap(
@@ -9294,7 +9320,7 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
     // taken by rvalue, but computing the size first prevents any changes in the
     // argument types of the constructor from breaking this.
     const uint32_t numRowExplicitTracks =
-        IsSubgrid(eLogicalAxisBlock)
+        IsSubgrid(LogicalAxis::Block)
             ? rowTrackSizes.Length()
             : gridReflowInput.mRowFunctions.NumExplicitTracks();
     // Row info has to accommodate fragmentation of the grid, which may happen
@@ -9307,7 +9333,7 @@ void nsGridContainerFrame::Reflow(nsPresContext* aPresContext,
         std::move(rowRemovedRepeatTracks),
         gridReflowInput.mRowFunctions.mRepeatAutoStart,
         rowLineNameMap.GetResolvedLineNamesForComputedGridTrackInfo(),
-        IsSubgrid(eLogicalAxisBlock), IsMasonry(eLogicalAxisBlock));
+        IsSubgrid(LogicalAxis::Block), IsMasonry(LogicalAxis::Block));
     SetProperty(GridRowTrackInfo(), rowInfo);
 
     if (prevInFlow) {
@@ -9613,16 +9639,16 @@ nscoord nsGridContainerFrame::IntrinsicISize(gfxContext* aRenderingContext,
   // They're only used for auto-repeat so we skip computing them otherwise.
   RepeatTrackSizingInput repeatSizing(state.mWM);
   if (!IsColSubgrid() && state.mColFunctions.mHasRepeatAuto) {
-    repeatSizing.InitFromStyle(eLogicalAxisInline, state.mWM,
+    repeatSizing.InitFromStyle(LogicalAxis::Inline, state.mWM,
                                state.mFrame->Style());
   }
   if ((!IsRowSubgrid() && state.mRowFunctions.mHasRepeatAuto &&
        !(state.mGridStyle->mGridAutoFlow & StyleGridAutoFlow::ROW)) ||
-      IsMasonry(eLogicalAxisInline)) {
+      IsMasonry(LogicalAxis::Inline)) {
     // Only 'grid-auto-flow:column' can create new implicit columns, so that's
     // the only case where our block-size can affect the number of columns.
     // Masonry layout always depends on how many rows we have though.
-    repeatSizing.InitFromStyle(eLogicalAxisBlock, state.mWM,
+    repeatSizing.InitFromStyle(LogicalAxis::Block, state.mWM,
                                state.mFrame->Style());
   }
 
@@ -9640,13 +9666,13 @@ nscoord nsGridContainerFrame::IntrinsicISize(gfxContext* aRenderingContext,
   auto constraint = aType == IntrinsicISizeType::MinISize
                         ? SizingConstraint::MinContent
                         : SizingConstraint::MaxContent;
-  if (IsMasonry(eLogicalAxisInline)) {
+  if (IsMasonry(LogicalAxis::Inline)) {
     ReflowOutput desiredSize(state.mWM);
     nsSize containerSize;
     LogicalRect contentArea(state.mWM);
     nsReflowStatus status;
     state.mRows.mSizes.SetLength(grid.mGridRowEnd);
-    state.CalculateTrackSizesForAxis(eLogicalAxisInline, grid,
+    state.CalculateTrackSizesForAxis(LogicalAxis::Inline, grid,
                                      NS_UNCONSTRAINEDSIZE, constraint);
     return MasonryLayout(state, contentArea, constraint, desiredSize, status,
                          nullptr, containerSize);
@@ -9656,7 +9682,7 @@ nscoord nsGridContainerFrame::IntrinsicISize(gfxContext* aRenderingContext,
     return nscoord(0);
   }
 
-  state.CalculateTrackSizesForAxis(eLogicalAxisInline, grid,
+  state.CalculateTrackSizesForAxis(LogicalAxis::Inline, grid,
                                    NS_UNCONSTRAINEDSIZE, constraint);
 
   if (MOZ_LIKELY(!IsSubgrid())) {
@@ -9672,7 +9698,6 @@ nscoord nsGridContainerFrame::GetMinISize(gfxContext* aRC) {
     return f->GetMinISize(aRC);
   }
 
-  DISPLAY_MIN_INLINE_SIZE(this, mCachedMinISize);
   if (mCachedMinISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
     Maybe<nscoord> containISize = ContainIntrinsicISize();
     mCachedMinISize = containISize
@@ -9688,7 +9713,6 @@ nscoord nsGridContainerFrame::GetPrefISize(gfxContext* aRC) {
     return f->GetPrefISize(aRC);
   }
 
-  DISPLAY_PREF_INLINE_SIZE(this, mCachedPrefISize);
   if (mCachedPrefISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
     Maybe<nscoord> containISize = ContainIntrinsicISize();
     mCachedPrefISize = containISize
@@ -9770,7 +9794,7 @@ StyleAlignFlags nsGridContainerFrame::CSSAlignmentForAbsPosChild(
              "This method should only be called for abspos children");
 
   StyleAlignFlags alignment =
-      (aLogicalAxis == eLogicalAxisInline)
+      (aLogicalAxis == LogicalAxis::Inline)
           ? aChildRI.mStylePosition->UsedJustifySelf(Style())._0
           : aChildRI.mStylePosition->UsedAlignSelf(Style())._0;
 
@@ -9792,7 +9816,7 @@ StyleAlignFlags nsGridContainerFrame::CSSAlignmentForAbsPosChild(
     alignment = StyleAlignFlags::END;
   } else if (alignment == StyleAlignFlags::LEFT ||
              alignment == StyleAlignFlags::RIGHT) {
-    if (aLogicalAxis == eLogicalAxisInline) {
+    if (aLogicalAxis == LogicalAxis::Inline) {
       const bool isLeft = (alignment == StyleAlignFlags::LEFT);
       WritingMode wm = GetWritingMode();
       alignment = (isLeft == wm.IsBidiLTR()) ? StyleAlignFlags::START
@@ -9827,7 +9851,7 @@ nscoord nsGridContainerFrame::SynthesizeBaseline(
   nscoord start;
   nscoord size;
 
-  if (aAxis == eLogicalAxisBlock) {
+  if (aAxis == LogicalAxis::Block) {
     start = child->GetLogicalNormalPosition(aCBWM, aCBPhysicalSize).B(aCBWM);
     size = child->BSize(aCBWM);
     if (grid && aGridOrderItem.mIsInEdgeTrack) {
@@ -9836,13 +9860,13 @@ nscoord nsGridContainerFrame::SynthesizeBaseline(
     } else if (!isOrthogonal && aGridOrderItem.mIsInEdgeTrack) {
       // This assertion is mostly for documentation purposes; it must hold,
       // given the checks in our 'if' statements. (We know aAxis is
-      // eLogicalAxisBlock, and isOrthogonal is false, which means childAxis
-      // must be eLogicalAxisBlock). If instead we got here with a childAxis of
-      // eLogicalAxisInline, then our call to
+      // LogicalAxis::Block, and isOrthogonal is false, which means childAxis
+      // must be LogicalAxis::Block). If instead we got here with a childAxis of
+      // LogicalAxis::Inline, then our call to
       // Baseline::SynthesizeBaselineFromBorderBox might incorrectly think
       // it makes sense to use a central baseline, in an axis where that
       // doesn't make sense.
-      MOZ_ASSERT(childAxis == eLogicalAxisBlock, "unexpected childAxis");
+      MOZ_ASSERT(childAxis == LogicalAxis::Block, "unexpected childAxis");
       baseline = child
                      ->GetNaturalBaselineBOffset(childWM, aGroup,
                                                  BaselineExportContext::Other)
@@ -9893,8 +9917,8 @@ void nsGridContainerFrame::CalculateBaselines(
   } else if (firstBaseline == NS_INTRINSIC_ISIZE_UNKNOWN) {
     FindItemInGridOrderResult gridOrderFirstItem = FindFirstItemInGridOrder(
         *aIter, *aGridItems,
-        axis == eLogicalAxisBlock ? &GridArea::mRows : &GridArea::mCols,
-        axis == eLogicalAxisBlock ? &GridArea::mCols : &GridArea::mRows,
+        axis == LogicalAxis::Block ? &GridArea::mRows : &GridArea::mCols,
+        axis == LogicalAxis::Block ? &GridArea::mCols : &GridArea::mRows,
         aFragmentStartTrack);
     mBaseline[axis][BaselineSharingGroup::First] = SynthesizeBaseline(
         gridOrderFirstItem, axis, BaselineSharingGroup::First, aCBPhysicalSize,
@@ -9929,8 +9953,8 @@ void nsGridContainerFrame::CalculateBaselines(
     iter.SetItemCount(aGridItems->Length());
     FindItemInGridOrderResult gridOrderLastItem = FindLastItemInGridOrder(
         iter, *aGridItems,
-        axis == eLogicalAxisBlock ? &GridArea::mRows : &GridArea::mCols,
-        axis == eLogicalAxisBlock ? &GridArea::mCols : &GridArea::mRows,
+        axis == LogicalAxis::Block ? &GridArea::mRows : &GridArea::mCols,
+        axis == LogicalAxis::Block ? &GridArea::mCols : &GridArea::mRows,
         aFragmentStartTrack, aFirstExcludedTrack);
     mBaseline[axis][BaselineSharingGroup::Last] =
         SynthesizeBaseline(gridOrderLastItem, axis, BaselineSharingGroup::Last,
@@ -10124,7 +10148,7 @@ bool nsGridContainerFrame::GridItemShouldStretch(const nsIFrame* aChild,
   }
 
   const auto* pos = aChild->StylePosition();
-  const auto alignment = (aAxis == eLogicalAxisInline) == !isOrthogonal
+  const auto alignment = (aAxis == LogicalAxis::Inline) == !isOrthogonal
                              ? pos->UsedJustifySelf(Style())._0
                              : pos->UsedAlignSelf(Style())._0;
   return alignment == StyleAlignFlags::NORMAL ||
diff --git a/layout/generic/nsGridContainerFrame.h b/layout/generic/nsGridContainerFrame.h
index cf3a3b5776..cb3eef68c3 100644
--- a/layout/generic/nsGridContainerFrame.h
+++ b/layout/generic/nsGridContainerFrame.h
@@ -233,12 +233,12 @@ class nsGridContainerFrame final : public nsContainerFrame,
 
   /** Return true if this frame is subgridded in its aAxis. */
   bool IsSubgrid(LogicalAxis aAxis) const {
-    return HasAnyStateBits(aAxis == mozilla::eLogicalAxisBlock
+    return HasAnyStateBits(aAxis == mozilla::LogicalAxis::Block
                                ? NS_STATE_GRID_IS_ROW_SUBGRID
                                : NS_STATE_GRID_IS_COL_SUBGRID);
   }
-  bool IsColSubgrid() const { return IsSubgrid(mozilla::eLogicalAxisInline); }
-  bool IsRowSubgrid() const { return IsSubgrid(mozilla::eLogicalAxisBlock); }
+  bool IsColSubgrid() const { return IsSubgrid(mozilla::LogicalAxis::Inline); }
+  bool IsRowSubgrid() const { return IsSubgrid(mozilla::LogicalAxis::Block); }
   /** Return true if this frame is subgridded in any axis. */
   bool IsSubgrid() const {
     return HasAnyStateBits(NS_STATE_GRID_IS_ROW_SUBGRID |
@@ -247,7 +247,7 @@ class nsGridContainerFrame final : public nsContainerFrame,
 
   /** Return true if this frame has an item that is subgridded in our aAxis. */
   bool HasSubgridItems(LogicalAxis aAxis) const {
-    return HasAnyStateBits(aAxis == mozilla::eLogicalAxisBlock
+    return HasAnyStateBits(aAxis == mozilla::LogicalAxis::Block
                                ? NS_STATE_GRID_HAS_ROW_SUBGRID_ITEM
                                : NS_STATE_GRID_HAS_COL_SUBGRID_ITEM);
   }
@@ -375,10 +375,10 @@ class nsGridContainerFrame final : public nsContainerFrame,
                          mozilla::IntrinsicISizeType aConstraint);
 
   nscoord GetBBaseline(BaselineSharingGroup aBaselineGroup) const {
-    return mBaseline[mozilla::eLogicalAxisBlock][aBaselineGroup];
+    return mBaseline[mozilla::LogicalAxis::Block][aBaselineGroup];
   }
   nscoord GetIBaseline(BaselineSharingGroup aBaselineGroup) const {
-    return mBaseline[mozilla::eLogicalAxisInline][aBaselineGroup];
+    return mBaseline[mozilla::LogicalAxis::Inline][aBaselineGroup];
   }
 
   /**
diff --git a/layout/generic/nsHTMLCanvasFrame.cpp b/layout/generic/nsHTMLCanvasFrame.cpp
index 07aeabec07..4b646359e5 100644
--- a/layout/generic/nsHTMLCanvasFrame.cpp
+++ b/layout/generic/nsHTMLCanvasFrame.cpp
@@ -382,7 +382,6 @@ nscoord nsHTMLCanvasFrame::GetMinISize(gfxContext* aRenderingContext) {
     result = nsPresContext::CSSPixelsToAppUnits(
         vertical ? GetCanvasSize().height : GetCanvasSize().width);
   }
-  DISPLAY_MIN_INLINE_SIZE(this, result);
   return result;
 }
 
@@ -398,7 +397,6 @@ nscoord nsHTMLCanvasFrame::GetPrefISize(gfxContext* aRenderingContext) {
     result = nsPresContext::CSSPixelsToAppUnits(
         vertical ? GetCanvasSize().height : GetCanvasSize().width);
   }
-  DISPLAY_PREF_INLINE_SIZE(this, result);
   return result;
 }
 
@@ -438,7 +436,6 @@ void nsHTMLCanvasFrame::Reflow(nsPresContext* aPresContext,
                                nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsHTMLCanvasFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
diff --git a/layout/generic/nsIFrame.cpp b/layout/generic/nsIFrame.cpp
index 479c26d18b..27f09b84f6 100644
--- a/layout/generic/nsIFrame.cpp
+++ b/layout/generic/nsIFrame.cpp
@@ -2017,6 +2017,12 @@ bool nsIFrame::GetShapeBoxBorderRadii(nscoord aRadii[8]) const {
   }
 }
 
+nscoord nsIFrame::OneEmInAppUnits() const {
+  return StyleFont()
+      ->mFont.size.ScaledBy(nsLayoutUtils::FontSizeInflationFor(this))
+      .ToAppUnits();
+}
+
 ComputedStyle* nsIFrame::GetAdditionalComputedStyle(int32_t aIndex) const {
   MOZ_ASSERT(aIndex >= 0, "invalid index number");
   return nullptr;
@@ -2396,6 +2402,15 @@ already_AddRefed<ComputedStyle> nsIFrame::ComputeHighlightSelectionStyle(
       *element, PseudoStyleType::highlight, aHighlightName, Style());
 }
 
+already_AddRefed<ComputedStyle> nsIFrame::ComputeTargetTextStyle() const {
+  const Element* element = FindElementAncestorForMozSelection(GetContent());
+  if (!element) {
+    return nullptr;
+  }
+  return PresContext()->StyleSet()->ProbePseudoElementStyle(
+      *element, PseudoStyleType::targetText, nullptr, Style());
+}
+
 template <typename SizeOrMaxSize>
 static inline bool IsIntrinsicKeyword(const SizeOrMaxSize& aSize) {
   // All keywords other than auto/none/-moz-available depend on intrinsic sizes.
@@ -4039,6 +4054,13 @@ void nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder* aBuilder,
     return;
   }
 
+  nsIFrame* child = aChild;
+  auto* placeholder = child->IsPlaceholderFrame()
+                          ? static_cast<nsPlaceholderFrame*>(child)
+                          : nullptr;
+  nsIFrame* childOrOutOfFlow =
+      placeholder ? placeholder->GetOutOfFlowFrame() : child;
+
   // If we're generating a display list for printing, include Link items for
   // frames that correspond to HTML link elements so that we can have active
   // links in saved PDF output. Note that the state of "within a link" is
@@ -4050,17 +4072,10 @@ void nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder* aBuilder,
   Maybe<nsDisplayListBuilder::Linkifier> linkifier;
   if (StaticPrefs::print_save_as_pdf_links_enabled() &&
       aBuilder->IsForPrinting()) {
-    linkifier.emplace(aBuilder, aChild, aLists.Content());
-    linkifier->MaybeAppendLink(aBuilder, aChild);
+    linkifier.emplace(aBuilder, childOrOutOfFlow, aLists.Content());
+    linkifier->MaybeAppendLink(aBuilder, childOrOutOfFlow);
   }
 
-  nsIFrame* child = aChild;
-  auto* placeholder = child->IsPlaceholderFrame()
-                          ? static_cast<nsPlaceholderFrame*>(child)
-                          : nullptr;
-  nsIFrame* childOrOutOfFlow =
-      placeholder ? placeholder->GetOutOfFlowFrame() : child;
-
   nsIFrame* parent = childOrOutOfFlow->GetParent();
   const auto* parentDisplay = parent->StyleDisplay();
   const auto overflowClipAxes =
@@ -5120,7 +5135,9 @@ nsresult nsIFrame::PeekBackwardAndForward(nsSelectionAmount aAmountBack,
     return rv;
   }
   if (aAmountBack == eSelectWord) {
-    frameSelection->SetIsDoubleClickSelection(true);
+    frameSelection->SetClickSelectionType(ClickSelectionType::Double);
+  } else if (aAmountBack == eSelectParagraph) {
+    frameSelection->SetClickSelectionType(ClickSelectionType::Triple);
   }
 
   // maintain selection
@@ -5989,18 +6006,10 @@ void nsIFrame::MarkSubtreeDirty() {
 }
 
 /* virtual */
-nscoord nsIFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  return result;
-}
+nscoord nsIFrame::GetMinISize(gfxContext* aRenderingContext) { return 0; }
 
 /* virtual */
-nscoord nsIFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  return result;
-}
+nscoord nsIFrame::GetPrefISize(gfxContext* aRenderingContext) { return 0; }
 
 /* virtual */
 void nsIFrame::AddInlineMinISize(gfxContext* aRenderingContext,
@@ -6319,14 +6328,12 @@ static MinMaxSize ComputeTransferredMinMaxInlineSize(
 
   if (aMinMaxBSize.mMinSize > 0) {
     transferredISize.mMinSize = aAspectRatio.ComputeRatioDependentSize(
-        LogicalAxis::eLogicalAxisInline, aWM, aMinMaxBSize.mMinSize,
-        aBoxSizingAdjustment);
+        LogicalAxis::Inline, aWM, aMinMaxBSize.mMinSize, aBoxSizingAdjustment);
   }
 
   if (aMinMaxBSize.mMaxSize != NS_UNCONSTRAINEDSIZE) {
     transferredISize.mMaxSize = aAspectRatio.ComputeRatioDependentSize(
-        LogicalAxis::eLogicalAxisInline, aWM, aMinMaxBSize.mMaxSize,
-        aBoxSizingAdjustment);
+        LogicalAxis::Inline, aWM, aMinMaxBSize.mMaxSize, aBoxSizingAdjustment);
   }
 
   // Minimum size wins over maximum size.
@@ -6393,11 +6400,11 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
   // indicates which axis (in this frame's own WM) corresponds to its
   // flex container's main axis.
   LogicalAxis flexMainAxis =
-      eLogicalAxisInline;  // (init to make valgrind happy)
+      LogicalAxis::Inline;  // (init to make valgrind happy)
   if (isFlexItem) {
     flexMainAxis = nsFlexContainerFrame::IsItemInlineAxisMainAxis(this)
-                       ? eLogicalAxisInline
-                       : eLogicalAxisBlock;
+                       ? LogicalAxis::Inline
+                       : LogicalAxis::Block;
   }
 
   const bool isOrthogonal = aWM.IsOrthogonalTo(alignCB->GetWritingMode());
@@ -6426,8 +6433,8 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
     bool mayUseAspectRatio = aspectRatio && !isAutoBSize;
     if (!aFlags.contains(ComputeSizeFlag::ShrinkWrap) &&
         !StyleMargin()->HasInlineAxisAuto(aWM) &&
-        !alignCB->IsMasonry(isOrthogonal ? eLogicalAxisBlock
-                                         : eLogicalAxisInline)) {
+        !alignCB->IsMasonry(isOrthogonal ? LogicalAxis::Block
+                                         : LogicalAxis::Inline)) {
       auto inlineAxisAlignment =
           isOrthogonal ? StylePosition()->UsedAlignSelf(alignCB->Style())._0
                        : StylePosition()->UsedJustifySelf(alignCB->Style())._0;
@@ -6451,7 +6458,7 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
           aCBSize.BSize(aWM), boxSizingAdjust.BSize(aWM),
           styleBSize.AsLengthPercentage());
       result.ISize(aWM) = aspectRatio.ComputeRatioDependentSize(
-          LogicalAxis::eLogicalAxisInline, aWM, bSize, boxSizingAdjust);
+          LogicalAxis::Inline, aWM, bSize, boxSizingAdjust);
       aspectRatioUsage = AspectRatioUsage::ToComputeISize;
     }
 
@@ -6468,7 +6475,7 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
         aCBSize.BSize(aWM), boxSizingAdjust.BSize(aWM),
         styleBSize.AsLengthPercentage());
     result.ISize(aWM) = aspectRatio.ComputeRatioDependentSize(
-        LogicalAxis::eLogicalAxisInline, aWM, bSize, boxSizingAdjust);
+        LogicalAxis::Inline, aWM, bSize, boxSizingAdjust);
     aspectRatioUsage = AspectRatioUsage::ToComputeISize;
   }
 
@@ -6523,7 +6530,7 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
   // flex container's main-axis.  (Those properties get applied later in
   // the flexbox algorithm.)
   const bool isFlexItemInlineAxisMainAxis =
-      isFlexItem && flexMainAxis == eLogicalAxisInline;
+      isFlexItem && flexMainAxis == LogicalAxis::Inline;
   // Grid items that are subgridded in inline-axis also ignore their min & max
   // sizing properties in that axis.
   const bool shouldIgnoreMinMaxISize =
@@ -6602,8 +6609,8 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
   } else if (MOZ_UNLIKELY(isGridItem) && styleBSize.IsAuto() &&
              !aFlags.contains(ComputeSizeFlag::IsGridMeasuringReflow) &&
              !IsTrueOverflowContainer() &&
-             !alignCB->IsMasonry(isOrthogonal ? eLogicalAxisInline
-                                              : eLogicalAxisBlock)) {
+             !alignCB->IsMasonry(isOrthogonal ? LogicalAxis::Inline
+                                              : LogicalAxis::Block)) {
     auto cbSize = aCBSize.BSize(aWM);
     if (cbSize != NS_UNCONSTRAINEDSIZE) {
       // 'auto' block-size for grid-level box - fill the CB for 'stretch' /
@@ -6628,8 +6635,7 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
       // https://drafts.csswg.org/css-grid/#grid-item-sizing
       if (!stretch && mayUseAspectRatio) {
         result.BSize(aWM) = aspectRatio.ComputeRatioDependentSize(
-            LogicalAxis::eLogicalAxisBlock, aWM, result.ISize(aWM),
-            boxSizingAdjust);
+            LogicalAxis::Block, aWM, result.ISize(aWM), boxSizingAdjust);
         MOZ_ASSERT(aspectRatioUsage == AspectRatioUsage::None);
         aspectRatioUsage = AspectRatioUsage::ToComputeBSize;
       }
@@ -6651,8 +6657,7 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
     // applied (so aspectRatioUsage flag is set as expected). That's why we
     // apply aspect-ratio unconditionally for auto block size here.
     result.BSize(aWM) = aspectRatio.ComputeRatioDependentSize(
-        LogicalAxis::eLogicalAxisBlock, aWM, result.ISize(aWM),
-        boxSizingAdjust);
+        LogicalAxis::Block, aWM, result.ISize(aWM), boxSizingAdjust);
     MOZ_ASSERT(aspectRatioUsage == AspectRatioUsage::None);
     aspectRatioUsage = AspectRatioUsage::ToComputeBSize;
   }
@@ -6662,7 +6667,7 @@ nsIFrame::SizeComputationResult nsIFrame::ComputeSize(
     // container's main-axis. (Those properties get applied later in the flexbox
     // algorithm.)
     const bool isFlexItemBlockAxisMainAxis =
-        isFlexItem && flexMainAxis == eLogicalAxisBlock;
+        isFlexItem && flexMainAxis == LogicalAxis::Block;
     // Grid items that are subgridded in block-axis also ignore their min & max
     // sizing properties in that axis.
     const bool shouldIgnoreMinMaxBSize =
@@ -6789,7 +6794,7 @@ Maybe<nscoord> nsIFrame::ComputeInlineSizeFromAspectRatio(
       aCBSize.BSize(aWM), aContentEdgeToBoxSizing.BSize(aWM),
       styleBSize.AsLengthPercentage());
   return Some(aspectRatio.ComputeRatioDependentSize(
-      LogicalAxis::eLogicalAxisInline, aWM, bSize, aContentEdgeToBoxSizing));
+      LogicalAxis::Inline, aWM, bSize, aContentEdgeToBoxSizing));
 }
 
 nsIFrame::ISizeComputationResult nsIFrame::ComputeISizeValue(
@@ -8560,6 +8565,12 @@ const nsFrameSelection* nsIFrame::GetConstFrameSelection() const {
 bool nsIFrame::IsFrameSelected() const {
   NS_ASSERTION(!GetContent() || GetContent()->IsMaybeSelected(),
                "use the public IsSelected() instead");
+  if (StaticPrefs::dom_shadowdom_selection_across_boundary_enabled()) {
+    if (const ShadowRoot* shadowRoot =
+            GetContent()->GetShadowRootForSelection()) {
+      return shadowRoot->IsSelected(0, shadowRoot->GetChildCount());
+    }
+  }
   return GetContent()->IsSelected(0, GetContent()->GetChildCount());
 }
 
@@ -8983,6 +8994,13 @@ nsresult nsIFrame::PeekOffsetForParagraph(PeekOffsetStruct* aPos) {
 
   if (reachedLimit) {  // no "stop frame" found
     aPos->mResultContent = frame->GetContent();
+    if (ShadowRoot* shadowRoot =
+            aPos->mResultContent->GetShadowRootForSelection()) {
+      // Even if there's no children for this node,
+      // the elements inside the shadow root is still
+      // selectable
+      aPos->mResultContent = shadowRoot;
+    }
     if (aPos->mDirection == eDirPrevious) {
       aPos->mContentOffset = 0;
     } else if (aPos->mResultContent) {
@@ -10698,21 +10716,27 @@ ComputedStyle* nsIFrame::DoGetParentComputedStyle(
 }
 
 void nsIFrame::GetLastLeaf(nsIFrame** aFrame) {
-  if (!aFrame || !*aFrame) return;
-  nsIFrame* child = *aFrame;
-  // if we are a block frame then go for the last line of 'this'
-  while (1) {
-    child = child->PrincipalChildList().FirstChild();
-    if (!child) return;  // nothing to do
-    nsIFrame* siblingFrame;
-    nsIContent* content;
-    // ignore anonymous elements, e.g. mozTableAdd* mozTableRemove*
-    // see bug 278197 comment #12 #13 for details
-    while ((siblingFrame = child->GetNextSibling()) &&
-           (content = siblingFrame->GetContent()) &&
-           !content->IsRootOfNativeAnonymousSubtree())
-      child = siblingFrame;
-    *aFrame = child;
+  if (!aFrame || !*aFrame) {
+    return;
+  }
+  for (nsIFrame* maybeLastLeaf = (*aFrame)->PrincipalChildList().LastChild();
+       maybeLastLeaf;) {
+    nsIFrame* lastChildNotInSubTree = nullptr;
+    for (nsIFrame* child = maybeLastLeaf; child;
+         child = child->GetPrevSibling()) {
+      nsIContent* content = child->GetContent();
+      // ignore anonymous elements, e.g. mozTableAdd* mozTableRemove*
+      // see bug 278197 comment #12 #13 for details
+      if (content && !content->IsRootOfNativeAnonymousSubtree()) {
+        lastChildNotInSubTree = child;
+        break;
+      }
+    }
+    if (!lastChildNotInSubTree) {
+      return;
+    }
+    *aFrame = lastChildNotInSubTree;
+    maybeLastLeaf = lastChildNotInSubTree->PrincipalChildList().LastChild();
   }
 }
 
@@ -10907,7 +10931,7 @@ void nsIFrame::UpdateStyleOfChildAnonBox(nsIFrame* aChildFrame,
   // Now that we've updated the style on aChildFrame, check whether it itself
   // has anon boxes to deal with.
   ServoRestyleState childrenState(*aChildFrame, aRestyleState, childHint,
-                                  ServoRestyleState::Type::InFlow);
+                                  ServoRestyleState::CanUseHandledHints::Yes);
   aChildFrame->UpdateStyleOfOwnedAnonBoxes(childrenState);
 
   // Assuming anon boxes don't have ::backdrop associated with them... if that
@@ -11655,1037 +11679,6 @@ void nsIFrame::VerifyDirtyBitSet(const nsFrameList& aFrameList) {
   }
 }
 
-// Start Display Reflow
-DR_cookie::DR_cookie(nsPresContext* aPresContext, nsIFrame* aFrame,
-                     const ReflowInput& aReflowInput, ReflowOutput& aMetrics,
-                     nsReflowStatus& aStatus)
-    : mPresContext(aPresContext),
-      mFrame(aFrame),
-      mReflowInput(aReflowInput),
-      mMetrics(aMetrics),
-      mStatus(aStatus) {
-  MOZ_COUNT_CTOR(DR_cookie);
-  mValue = nsIFrame::DisplayReflowEnter(aPresContext, mFrame, mReflowInput);
-}
-
-DR_cookie::~DR_cookie() {
-  MOZ_COUNT_DTOR(DR_cookie);
-  nsIFrame::DisplayReflowExit(mPresContext, mFrame, mMetrics, mStatus, mValue);
-}
-
-DR_layout_cookie::DR_layout_cookie(nsIFrame* aFrame) : mFrame(aFrame) {
-  MOZ_COUNT_CTOR(DR_layout_cookie);
-  mValue = nsIFrame::DisplayLayoutEnter(mFrame);
-}
-
-DR_layout_cookie::~DR_layout_cookie() {
-  MOZ_COUNT_DTOR(DR_layout_cookie);
-  nsIFrame::DisplayLayoutExit(mFrame, mValue);
-}
-
-DR_intrinsic_inline_size_cookie::DR_intrinsic_inline_size_cookie(
-    nsIFrame* aFrame, const char* aType, nscoord& aResult)
-    : mFrame(aFrame), mType(aType), mResult(aResult) {
-  MOZ_COUNT_CTOR(DR_intrinsic_inline_size_cookie);
-  mValue = nsIFrame::DisplayIntrinsicISizeEnter(mFrame, mType);
-}
-
-DR_intrinsic_inline_size_cookie::~DR_intrinsic_inline_size_cookie() {
-  MOZ_COUNT_DTOR(DR_intrinsic_inline_size_cookie);
-  nsIFrame::DisplayIntrinsicISizeExit(mFrame, mType, mResult, mValue);
-}
-
-DR_intrinsic_size_cookie::DR_intrinsic_size_cookie(nsIFrame* aFrame,
-                                                   const char* aType,
-                                                   nsSize& aResult)
-    : mFrame(aFrame), mType(aType), mResult(aResult) {
-  MOZ_COUNT_CTOR(DR_intrinsic_size_cookie);
-  mValue = nsIFrame::DisplayIntrinsicSizeEnter(mFrame, mType);
-}
-
-DR_intrinsic_size_cookie::~DR_intrinsic_size_cookie() {
-  MOZ_COUNT_DTOR(DR_intrinsic_size_cookie);
-  nsIFrame::DisplayIntrinsicSizeExit(mFrame, mType, mResult, mValue);
-}
-
-DR_init_constraints_cookie::DR_init_constraints_cookie(
-    nsIFrame* aFrame, ReflowInput* aState, nscoord aCBWidth, nscoord aCBHeight,
-    const mozilla::Maybe<mozilla::LogicalMargin> aBorder,
-    const mozilla::Maybe<mozilla::LogicalMargin> aPadding)
-    : mFrame(aFrame), mState(aState) {
-  MOZ_COUNT_CTOR(DR_init_constraints_cookie);
-  nsMargin border;
-  if (aBorder) {
-    border = aBorder->GetPhysicalMargin(aFrame->GetWritingMode());
-  }
-  nsMargin padding;
-  if (aPadding) {
-    padding = aPadding->GetPhysicalMargin(aFrame->GetWritingMode());
-  }
-  mValue = ReflowInput::DisplayInitConstraintsEnter(
-      mFrame, mState, aCBWidth, aCBHeight, aBorder ? &border : nullptr,
-      aPadding ? &padding : nullptr);
-}
-
-DR_init_constraints_cookie::~DR_init_constraints_cookie() {
-  MOZ_COUNT_DTOR(DR_init_constraints_cookie);
-  ReflowInput::DisplayInitConstraintsExit(mFrame, mState, mValue);
-}
-
-DR_init_offsets_cookie::DR_init_offsets_cookie(
-    nsIFrame* aFrame, SizeComputationInput* aState, nscoord aPercentBasis,
-    WritingMode aCBWritingMode,
-    const mozilla::Maybe<mozilla::LogicalMargin> aBorder,
-    const mozilla::Maybe<mozilla::LogicalMargin> aPadding)
-    : mFrame(aFrame), mState(aState) {
-  MOZ_COUNT_CTOR(DR_init_offsets_cookie);
-  nsMargin border;
-  if (aBorder) {
-    border = aBorder->GetPhysicalMargin(aFrame->GetWritingMode());
-  }
-  nsMargin padding;
-  if (aPadding) {
-    padding = aPadding->GetPhysicalMargin(aFrame->GetWritingMode());
-  }
-  mValue = SizeComputationInput::DisplayInitOffsetsEnter(
-      mFrame, mState, aPercentBasis, aCBWritingMode,
-      aBorder ? &border : nullptr, aPadding ? &padding : nullptr);
-}
-
-DR_init_offsets_cookie::~DR_init_offsets_cookie() {
-  MOZ_COUNT_DTOR(DR_init_offsets_cookie);
-  SizeComputationInput::DisplayInitOffsetsExit(mFrame, mState, mValue);
-}
-
-struct DR_Rule;
-
-struct DR_FrameTypeInfo {
-  DR_FrameTypeInfo(LayoutFrameType aFrameType, const char* aFrameNameAbbrev,
-                   const char* aFrameName);
-  ~DR_FrameTypeInfo();
-
-  LayoutFrameType mType;
-  char mNameAbbrev[16];
-  char mName[32];
-  nsTArray<DR_Rule*> mRules;
-
- private:
-  DR_FrameTypeInfo& operator=(const DR_FrameTypeInfo&) = delete;
-};
-
-struct DR_FrameTreeNode;
-struct DR_Rule;
-
-struct DR_State {
-  DR_State();
-  ~DR_State();
-  void Init();
-  void AddFrameTypeInfo(LayoutFrameType aFrameType,
-                        const char* aFrameNameAbbrev, const char* aFrameName);
-  DR_FrameTypeInfo* GetFrameTypeInfo(LayoutFrameType aFrameType);
-  DR_FrameTypeInfo* GetFrameTypeInfo(char* aFrameName);
-  void InitFrameTypeTable();
-  DR_FrameTreeNode* CreateTreeNode(nsIFrame* aFrame,
-                                   const ReflowInput* aReflowInput);
-  void FindMatchingRule(DR_FrameTreeNode& aNode);
-  bool RuleMatches(DR_Rule& aRule, DR_FrameTreeNode& aNode);
-  bool GetToken(FILE* aFile, char* aBuf, size_t aBufSize);
-  DR_Rule* ParseRule(FILE* aFile);
-  void ParseRulesFile();
-  void AddRule(nsTArray<DR_Rule*>& aRules, DR_Rule& aRule);
-  bool IsWhiteSpace(int c);
-  bool GetNumber(char* aBuf, int32_t& aNumber);
-  void PrettyUC(nscoord aSize, char* aBuf, int aBufSize);
-  void PrintMargin(const char* tag, const nsMargin* aMargin);
-  void DisplayFrameTypeInfo(nsIFrame* aFrame, int32_t aIndent);
-  void DeleteTreeNode(DR_FrameTreeNode& aNode);
-
-  bool mInited;
-  bool mActive;
-  int32_t mCount;
-  int32_t mAssert;
-  int32_t mIndent;
-  bool mIndentUndisplayedFrames;
-  bool mDisplayPixelErrors;
-  nsTArray<DR_Rule*> mWildRules;
-  nsTArray<DR_FrameTypeInfo> mFrameTypeTable;
-  // reflow specific state
-  nsTArray<DR_FrameTreeNode*> mFrameTreeLeaves;
-};
-
-static DR_State* DR_state;  // the one and only DR_State
-
-struct DR_RulePart {
-  explicit DR_RulePart(LayoutFrameType aFrameType)
-      : mFrameType(aFrameType), mNext(0) {}
-
-  void Destroy();
-
-  LayoutFrameType mFrameType;
-  DR_RulePart* mNext;
-};
-
-void DR_RulePart::Destroy() {
-  if (mNext) {
-    mNext->Destroy();
-  }
-  delete this;
-}
-
-struct DR_Rule {
-  DR_Rule() : mLength(0), mTarget(nullptr), mDisplay(false) {
-    MOZ_COUNT_CTOR(DR_Rule);
-  }
-  ~DR_Rule() {
-    if (mTarget) mTarget->Destroy();
-    MOZ_COUNT_DTOR(DR_Rule);
-  }
-  void AddPart(LayoutFrameType aFrameType);
-
-  uint32_t mLength;
-  DR_RulePart* mTarget;
-  bool mDisplay;
-};
-
-void DR_Rule::AddPart(LayoutFrameType aFrameType) {
-  DR_RulePart* newPart = new DR_RulePart(aFrameType);
-  newPart->mNext = mTarget;
-  mTarget = newPart;
-  mLength++;
-}
-
-DR_FrameTypeInfo::~DR_FrameTypeInfo() {
-  int32_t numElements;
-  numElements = mRules.Length();
-  for (int32_t i = numElements - 1; i >= 0; i--) {
-    delete mRules.ElementAt(i);
-  }
-}
-
-DR_FrameTypeInfo::DR_FrameTypeInfo(LayoutFrameType aFrameType,
-                                   const char* aFrameNameAbbrev,
-                                   const char* aFrameName) {
-  mType = aFrameType;
-  PL_strncpyz(mNameAbbrev, aFrameNameAbbrev, sizeof(mNameAbbrev));
-  PL_strncpyz(mName, aFrameName, sizeof(mName));
-}
-
-struct DR_FrameTreeNode {
-  DR_FrameTreeNode(nsIFrame* aFrame, DR_FrameTreeNode* aParent)
-      : mFrame(aFrame), mParent(aParent), mDisplay(0), mIndent(0) {
-    MOZ_COUNT_CTOR(DR_FrameTreeNode);
-  }
-
-  MOZ_COUNTED_DTOR(DR_FrameTreeNode)
-
-  nsIFrame* mFrame;
-  DR_FrameTreeNode* mParent;
-  bool mDisplay;
-  uint32_t mIndent;
-};
-
-// DR_State implementation
-
-DR_State::DR_State()
-    : mInited(false),
-      mActive(false),
-      mCount(0),
-      mAssert(-1),
-      mIndent(0),
-      mIndentUndisplayedFrames(false),
-      mDisplayPixelErrors(false) {
-  MOZ_COUNT_CTOR(DR_State);
-}
-
-void DR_State::Init() {
-  char* env = PR_GetEnv("GECKO_DISPLAY_REFLOW_ASSERT");
-  int32_t num;
-  if (env) {
-    if (GetNumber(env, num))
-      mAssert = num;
-    else
-      printf("GECKO_DISPLAY_REFLOW_ASSERT - invalid value = %s", env);
-  }
-
-  env = PR_GetEnv("GECKO_DISPLAY_REFLOW_INDENT_START");
-  if (env) {
-    if (GetNumber(env, num))
-      mIndent = num;
-    else
-      printf("GECKO_DISPLAY_REFLOW_INDENT_START - invalid value = %s", env);
-  }
-
-  env = PR_GetEnv("GECKO_DISPLAY_REFLOW_INDENT_UNDISPLAYED_FRAMES");
-  if (env) {
-    if (GetNumber(env, num))
-      mIndentUndisplayedFrames = num;
-    else
-      printf(
-          "GECKO_DISPLAY_REFLOW_INDENT_UNDISPLAYED_FRAMES - invalid value = %s",
-          env);
-  }
-
-  env = PR_GetEnv("GECKO_DISPLAY_REFLOW_FLAG_PIXEL_ERRORS");
-  if (env) {
-    if (GetNumber(env, num))
-      mDisplayPixelErrors = num;
-    else
-      printf("GECKO_DISPLAY_REFLOW_FLAG_PIXEL_ERRORS - invalid value = %s",
-             env);
-  }
-
-  InitFrameTypeTable();
-  ParseRulesFile();
-  mInited = true;
-}
-
-DR_State::~DR_State() {
-  MOZ_COUNT_DTOR(DR_State);
-  int32_t numElements, i;
-  numElements = mWildRules.Length();
-  for (i = numElements - 1; i >= 0; i--) {
-    delete mWildRules.ElementAt(i);
-  }
-  numElements = mFrameTreeLeaves.Length();
-  for (i = numElements - 1; i >= 0; i--) {
-    delete mFrameTreeLeaves.ElementAt(i);
-  }
-}
-
-bool DR_State::GetNumber(char* aBuf, int32_t& aNumber) {
-  if (sscanf(aBuf, "%d", &aNumber) > 0)
-    return true;
-  else
-    return false;
-}
-
-bool DR_State::IsWhiteSpace(int c) {
-  return (c == ' ') || (c == '\t') || (c == '\n') || (c == '\r');
-}
-
-bool DR_State::GetToken(FILE* aFile, char* aBuf, size_t aBufSize) {
-  bool haveToken = false;
-  aBuf[0] = 0;
-  // get the 1st non whitespace char
-  int c = -1;
-  for (c = getc(aFile); (c > 0) && IsWhiteSpace(c); c = getc(aFile)) {
-  }
-
-  if (c > 0) {
-    haveToken = true;
-    aBuf[0] = c;
-    // get everything up to the next whitespace char
-    size_t cX;
-    for (cX = 1; cX + 1 < aBufSize; cX++) {
-      c = getc(aFile);
-      if (c < 0) {  // EOF
-        ungetc(' ', aFile);
-        break;
-      } else {
-        if (IsWhiteSpace(c)) {
-          break;
-        } else {
-          aBuf[cX] = c;
-        }
-      }
-    }
-    aBuf[cX] = 0;
-  }
-  return haveToken;
-}
-
-DR_Rule* DR_State::ParseRule(FILE* aFile) {
-  char buf[128];
-  int32_t doDisplay;
-  DR_Rule* rule = nullptr;
-  while (GetToken(aFile, buf, sizeof(buf))) {
-    if (GetNumber(buf, doDisplay)) {
-      if (rule) {
-        rule->mDisplay = !!doDisplay;
-        break;
-      } else {
-        printf("unexpected token - %s \n", buf);
-      }
-    } else {
-      if (!rule) {
-        rule = new DR_Rule;
-      }
-      if (strcmp(buf, "*") == 0) {
-        rule->AddPart(LayoutFrameType::None);
-      } else {
-        DR_FrameTypeInfo* info = GetFrameTypeInfo(buf);
-        if (info) {
-          rule->AddPart(info->mType);
-        } else {
-          printf("invalid frame type - %s \n", buf);
-        }
-      }
-    }
-  }
-  return rule;
-}
-
-void DR_State::AddRule(nsTArray<DR_Rule*>& aRules, DR_Rule& aRule) {
-  int32_t numRules = aRules.Length();
-  for (int32_t ruleX = 0; ruleX < numRules; ruleX++) {
-    DR_Rule* rule = aRules.ElementAt(ruleX);
-    NS_ASSERTION(rule, "program error");
-    if (aRule.mLength > rule->mLength) {
-      aRules.InsertElementAt(ruleX, &aRule);
-      return;
-    }
-  }
-  aRules.AppendElement(&aRule);
-}
-
-static Maybe<bool> ShouldLogReflow(const char* processes) {
-  switch (processes[0]) {
-    case 'A':
-    case 'a':
-      return Some(true);
-    case 'P':
-    case 'p':
-      return Some(XRE_IsParentProcess());
-    case 'C':
-    case 'c':
-      return Some(XRE_IsContentProcess());
-    default:
-      return Nothing{};
-  }
-}
-
-void DR_State::ParseRulesFile() {
-  char* processes = PR_GetEnv("GECKO_DISPLAY_REFLOW_PROCESSES");
-  if (processes) {
-    Maybe<bool> enableLog = ShouldLogReflow(processes);
-    if (enableLog.isNothing()) {
-      MOZ_CRASH("GECKO_DISPLAY_REFLOW_PROCESSES: [a]ll [p]arent [c]ontent");
-    } else if (enableLog.value()) {
-      DR_Rule* rule = new DR_Rule;
-      rule->AddPart(LayoutFrameType::None);
-      rule->mDisplay = true;
-      AddRule(mWildRules, *rule);
-      mActive = true;
-    }
-    return;
-  }
-
-  char* path = PR_GetEnv("GECKO_DISPLAY_REFLOW_RULES_FILE");
-  if (path) {
-    FILE* inFile = fopen(path, "r");
-    if (!inFile) {
-      MOZ_CRASH(
-          "Failed to open the specified rules file; Try `--setpref "
-          "security.sandbox.content.level=2` if the sandbox is at cause");
-    }
-    for (DR_Rule* rule = ParseRule(inFile); rule; rule = ParseRule(inFile)) {
-      if (rule->mTarget) {
-        LayoutFrameType fType = rule->mTarget->mFrameType;
-        if (fType != LayoutFrameType::None) {
-          DR_FrameTypeInfo* info = GetFrameTypeInfo(fType);
-          AddRule(info->mRules, *rule);
-        } else {
-          AddRule(mWildRules, *rule);
-        }
-        mActive = true;
-      }
-    }
-
-    fclose(inFile);
-  }
-}
-
-void DR_State::AddFrameTypeInfo(LayoutFrameType aFrameType,
-                                const char* aFrameNameAbbrev,
-                                const char* aFrameName) {
-  mFrameTypeTable.EmplaceBack(aFrameType, aFrameNameAbbrev, aFrameName);
-}
-
-DR_FrameTypeInfo* DR_State::GetFrameTypeInfo(LayoutFrameType aFrameType) {
-  int32_t numEntries = mFrameTypeTable.Length();
-  NS_ASSERTION(numEntries != 0, "empty FrameTypeTable");
-  for (int32_t i = 0; i < numEntries; i++) {
-    DR_FrameTypeInfo& info = mFrameTypeTable.ElementAt(i);
-    if (info.mType == aFrameType) {
-      return &info;
-    }
-  }
-  return &mFrameTypeTable.ElementAt(numEntries -
-                                    1);  // return unknown frame type
-}
-
-DR_FrameTypeInfo* DR_State::GetFrameTypeInfo(char* aFrameName) {
-  int32_t numEntries = mFrameTypeTable.Length();
-  NS_ASSERTION(numEntries != 0, "empty FrameTypeTable");
-  for (int32_t i = 0; i < numEntries; i++) {
-    DR_FrameTypeInfo& info = mFrameTypeTable.ElementAt(i);
-    if ((strcmp(aFrameName, info.mName) == 0) ||
-        (strcmp(aFrameName, info.mNameAbbrev) == 0)) {
-      return &info;
-    }
-  }
-  return &mFrameTypeTable.ElementAt(numEntries -
-                                    1);  // return unknown frame type
-}
-
-void DR_State::InitFrameTypeTable() {
-  AddFrameTypeInfo(LayoutFrameType::Block, "block", "block");
-  AddFrameTypeInfo(LayoutFrameType::Br, "br", "br");
-  AddFrameTypeInfo(LayoutFrameType::ColorControl, "color", "colorControl");
-  AddFrameTypeInfo(LayoutFrameType::GfxButtonControl, "button",
-                   "gfxButtonControl");
-  AddFrameTypeInfo(LayoutFrameType::HTMLButtonControl, "HTMLbutton",
-                   "HTMLButtonControl");
-  AddFrameTypeInfo(LayoutFrameType::HTMLCanvas, "HTMLCanvas", "HTMLCanvas");
-  AddFrameTypeInfo(LayoutFrameType::SubDocument, "subdoc", "subDocument");
-  AddFrameTypeInfo(LayoutFrameType::Image, "img", "image");
-  AddFrameTypeInfo(LayoutFrameType::Inline, "inline", "inline");
-  AddFrameTypeInfo(LayoutFrameType::Letter, "letter", "letter");
-  AddFrameTypeInfo(LayoutFrameType::Line, "line", "line");
-  AddFrameTypeInfo(LayoutFrameType::ListControl, "select", "select");
-  AddFrameTypeInfo(LayoutFrameType::Page, "page", "page");
-  AddFrameTypeInfo(LayoutFrameType::Placeholder, "place", "placeholder");
-  AddFrameTypeInfo(LayoutFrameType::Canvas, "canvas", "canvas");
-  AddFrameTypeInfo(LayoutFrameType::Scroll, "scroll", "scroll");
-  AddFrameTypeInfo(LayoutFrameType::TableCell, "cell", "tableCell");
-  AddFrameTypeInfo(LayoutFrameType::TableCol, "col", "tableCol");
-  AddFrameTypeInfo(LayoutFrameType::TableColGroup, "colG", "tableColGroup");
-  AddFrameTypeInfo(LayoutFrameType::Table, "tbl", "table");
-  AddFrameTypeInfo(LayoutFrameType::TableWrapper, "tblW", "tableWrapper");
-  AddFrameTypeInfo(LayoutFrameType::TableRowGroup, "rowG", "tableRowGroup");
-  AddFrameTypeInfo(LayoutFrameType::TableRow, "row", "tableRow");
-  AddFrameTypeInfo(LayoutFrameType::TextInput, "textCtl", "textInput");
-  AddFrameTypeInfo(LayoutFrameType::Text, "text", "text");
-  AddFrameTypeInfo(LayoutFrameType::Viewport, "VP", "viewport");
-  AddFrameTypeInfo(LayoutFrameType::Slider, "Slider", "Slider");
-  AddFrameTypeInfo(LayoutFrameType::None, "unknown", "unknown");
-}
-
-void DR_State::DisplayFrameTypeInfo(nsIFrame* aFrame, int32_t aIndent) {
-  DR_FrameTypeInfo* frameTypeInfo = GetFrameTypeInfo(aFrame->Type());
-  if (frameTypeInfo) {
-    for (int32_t i = 0; i < aIndent; i++) {
-      printf(" ");
-    }
-    if (!strcmp(frameTypeInfo->mNameAbbrev, "unknown")) {
-      if (aFrame) {
-        nsAutoString name;
-        aFrame->GetFrameName(name);
-        printf("%s %p ", NS_LossyConvertUTF16toASCII(name).get(),
-               (void*)aFrame);
-      } else {
-        printf("%s %p ", frameTypeInfo->mNameAbbrev, (void*)aFrame);
-      }
-    } else {
-      printf("%s %p ", frameTypeInfo->mNameAbbrev, (void*)aFrame);
-    }
-  }
-}
-
-bool DR_State::RuleMatches(DR_Rule& aRule, DR_FrameTreeNode& aNode) {
-  NS_ASSERTION(aRule.mTarget, "program error");
-
-  DR_RulePart* rulePart;
-  DR_FrameTreeNode* parentNode;
-  for (rulePart = aRule.mTarget->mNext, parentNode = aNode.mParent;
-       rulePart && parentNode;
-       rulePart = rulePart->mNext, parentNode = parentNode->mParent) {
-    if (rulePart->mFrameType != LayoutFrameType::None) {
-      if (parentNode->mFrame) {
-        if (rulePart->mFrameType != parentNode->mFrame->Type()) {
-          return false;
-        }
-      } else
-        NS_ASSERTION(false, "program error");
-    }
-    // else wild card match
-  }
-  return true;
-}
-
-void DR_State::FindMatchingRule(DR_FrameTreeNode& aNode) {
-  if (!aNode.mFrame) {
-    NS_ASSERTION(false, "invalid DR_FrameTreeNode \n");
-    return;
-  }
-
-  bool matchingRule = false;
-
-  DR_FrameTypeInfo* info = GetFrameTypeInfo(aNode.mFrame->Type());
-  NS_ASSERTION(info, "program error");
-  int32_t numRules = info->mRules.Length();
-  for (int32_t ruleX = 0; ruleX < numRules; ruleX++) {
-    DR_Rule* rule = info->mRules.ElementAt(ruleX);
-    if (rule && RuleMatches(*rule, aNode)) {
-      aNode.mDisplay = rule->mDisplay;
-      matchingRule = true;
-      break;
-    }
-  }
-  if (!matchingRule) {
-    int32_t numWildRules = mWildRules.Length();
-    for (int32_t ruleX = 0; ruleX < numWildRules; ruleX++) {
-      DR_Rule* rule = mWildRules.ElementAt(ruleX);
-      if (rule && RuleMatches(*rule, aNode)) {
-        aNode.mDisplay = rule->mDisplay;
-        break;
-      }
-    }
-  }
-}
-
-DR_FrameTreeNode* DR_State::CreateTreeNode(nsIFrame* aFrame,
-                                           const ReflowInput* aReflowInput) {
-  // find the frame of the parent reflow input (usually just the parent of
-  // aFrame)
-  nsIFrame* parentFrame;
-  if (aReflowInput) {
-    const ReflowInput* parentRI = aReflowInput->mParentReflowInput;
-    parentFrame = (parentRI) ? parentRI->mFrame : nullptr;
-  } else {
-    parentFrame = aFrame->GetParent();
-  }
-
-  // find the parent tree node leaf
-  DR_FrameTreeNode* parentNode = nullptr;
-
-  DR_FrameTreeNode* lastLeaf = nullptr;
-  if (mFrameTreeLeaves.Length())
-    lastLeaf = mFrameTreeLeaves.ElementAt(mFrameTreeLeaves.Length() - 1);
-  if (lastLeaf) {
-    for (parentNode = lastLeaf;
-         parentNode && (parentNode->mFrame != parentFrame);
-         parentNode = parentNode->mParent) {
-    }
-  }
-  DR_FrameTreeNode* newNode = new DR_FrameTreeNode(aFrame, parentNode);
-  FindMatchingRule(*newNode);
-
-  newNode->mIndent = mIndent;
-  if (newNode->mDisplay || mIndentUndisplayedFrames) {
-    ++mIndent;
-  }
-
-  if (lastLeaf && (lastLeaf == parentNode)) {
-    mFrameTreeLeaves.RemoveLastElement();
-  }
-  mFrameTreeLeaves.AppendElement(newNode);
-  mCount++;
-
-  return newNode;
-}
-
-void DR_State::PrettyUC(nscoord aSize, char* aBuf, int aBufSize) {
-  if (NS_UNCONSTRAINEDSIZE == aSize) {
-    strcpy(aBuf, "UC");
-  } else {
-    if ((nscoord)0xdeadbeefU == aSize) {
-      strcpy(aBuf, "deadbeef");
-    } else {
-      snprintf(aBuf, aBufSize, "%d", aSize);
-    }
-  }
-}
-
-void DR_State::PrintMargin(const char* tag, const nsMargin* aMargin) {
-  if (aMargin) {
-    char t[16], r[16], b[16], l[16];
-    PrettyUC(aMargin->top, t, 16);
-    PrettyUC(aMargin->right, r, 16);
-    PrettyUC(aMargin->bottom, b, 16);
-    PrettyUC(aMargin->left, l, 16);
-    printf(" %s=%s,%s,%s,%s", tag, t, r, b, l);
-  } else {
-    // use %p here for consistency with other null-pointer printouts
-    printf(" %s=%p", tag, (void*)aMargin);
-  }
-}
-
-void DR_State::DeleteTreeNode(DR_FrameTreeNode& aNode) {
-  mFrameTreeLeaves.RemoveElement(&aNode);
-  int32_t numLeaves = mFrameTreeLeaves.Length();
-  if ((0 == numLeaves) ||
-      (aNode.mParent != mFrameTreeLeaves.ElementAt(numLeaves - 1))) {
-    mFrameTreeLeaves.AppendElement(aNode.mParent);
-  }
-
-  if (aNode.mDisplay || mIndentUndisplayedFrames) {
-    --mIndent;
-  }
-  // delete the tree node
-  delete &aNode;
-}
-
-static void CheckPixelError(nscoord aSize, int32_t aPixelToTwips) {
-  if (NS_UNCONSTRAINEDSIZE != aSize) {
-    if ((aSize % aPixelToTwips) > 0) {
-      printf("VALUE %d is not a whole pixel \n", aSize);
-    }
-  }
-}
-
-static void DisplayReflowEnterPrint(nsPresContext* aPresContext,
-                                    nsIFrame* aFrame,
-                                    const ReflowInput& aReflowInput,
-                                    DR_FrameTreeNode& aTreeNode,
-                                    bool aChanged) {
-  if (aTreeNode.mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, aTreeNode.mIndent);
-
-    char width[16];
-    char height[16];
-
-    DR_state->PrettyUC(aReflowInput.AvailableWidth(), width, 16);
-    DR_state->PrettyUC(aReflowInput.AvailableHeight(), height, 16);
-    printf("Reflow a=%s,%s ", width, height);
-
-    DR_state->PrettyUC(aReflowInput.ComputedWidth(), width, 16);
-    DR_state->PrettyUC(aReflowInput.ComputedHeight(), height, 16);
-    printf("c=%s,%s ", width, height);
-
-    if (aFrame->HasAnyStateBits(NS_FRAME_IS_DIRTY)) printf("dirty ");
-
-    if (aFrame->HasAnyStateBits(NS_FRAME_HAS_DIRTY_CHILDREN))
-      printf("dirty-children ");
-
-    if (aReflowInput.mFlags.mSpecialBSizeReflow) printf("special-bsize ");
-
-    if (aReflowInput.IsHResize()) printf("h-resize ");
-
-    if (aReflowInput.IsVResize()) printf("v-resize ");
-
-    nsIFrame* inFlow = aFrame->GetPrevInFlow();
-    if (inFlow) {
-      printf("pif=%p ", (void*)inFlow);
-    }
-    inFlow = aFrame->GetNextInFlow();
-    if (inFlow) {
-      printf("nif=%p ", (void*)inFlow);
-    }
-    if (aChanged)
-      printf("CHANGED \n");
-    else
-      printf("cnt=%d \n", DR_state->mCount);
-    if (DR_state->mDisplayPixelErrors) {
-      int32_t d2a = aPresContext->AppUnitsPerDevPixel();
-      CheckPixelError(aReflowInput.AvailableWidth(), d2a);
-      CheckPixelError(aReflowInput.AvailableHeight(), d2a);
-      CheckPixelError(aReflowInput.ComputedWidth(), d2a);
-      CheckPixelError(aReflowInput.ComputedHeight(), d2a);
-    }
-  }
-}
-
-void* nsIFrame::DisplayReflowEnter(nsPresContext* aPresContext,
-                                   nsIFrame* aFrame,
-                                   const ReflowInput& aReflowInput) {
-  if (!DR_state->mInited) DR_state->Init();
-  if (!DR_state->mActive) return nullptr;
-
-  NS_ASSERTION(aFrame, "invalid call");
-
-  DR_FrameTreeNode* treeNode = DR_state->CreateTreeNode(aFrame, &aReflowInput);
-  if (treeNode) {
-    DisplayReflowEnterPrint(aPresContext, aFrame, aReflowInput, *treeNode,
-                            false);
-  }
-  return treeNode;
-}
-
-void* nsIFrame::DisplayLayoutEnter(nsIFrame* aFrame) {
-  if (!DR_state->mInited) DR_state->Init();
-  if (!DR_state->mActive) return nullptr;
-
-  NS_ASSERTION(aFrame, "invalid call");
-
-  DR_FrameTreeNode* treeNode = DR_state->CreateTreeNode(aFrame, nullptr);
-  if (treeNode && treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    printf("XULLayout\n");
-  }
-  return treeNode;
-}
-
-void* nsIFrame::DisplayIntrinsicISizeEnter(nsIFrame* aFrame,
-                                           const char* aType) {
-  if (!DR_state->mInited) DR_state->Init();
-  if (!DR_state->mActive) return nullptr;
-
-  NS_ASSERTION(aFrame, "invalid call");
-
-  DR_FrameTreeNode* treeNode = DR_state->CreateTreeNode(aFrame, nullptr);
-  if (treeNode && treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    printf("Get%sISize\n", aType);
-  }
-  return treeNode;
-}
-
-void* nsIFrame::DisplayIntrinsicSizeEnter(nsIFrame* aFrame, const char* aType) {
-  if (!DR_state->mInited) DR_state->Init();
-  if (!DR_state->mActive) return nullptr;
-
-  NS_ASSERTION(aFrame, "invalid call");
-
-  DR_FrameTreeNode* treeNode = DR_state->CreateTreeNode(aFrame, nullptr);
-  if (treeNode && treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    printf("Get%sSize\n", aType);
-  }
-  return treeNode;
-}
-
-void nsIFrame::DisplayReflowExit(nsPresContext* aPresContext, nsIFrame* aFrame,
-                                 ReflowOutput& aMetrics,
-                                 const nsReflowStatus& aStatus,
-                                 void* aFrameTreeNode) {
-  if (!DR_state->mActive) return;
-
-  NS_ASSERTION(aFrame, "DisplayReflowExit - invalid call");
-  if (!aFrameTreeNode) return;
-
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)aFrameTreeNode;
-  if (treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-
-    char width[16];
-    char height[16];
-    char x[16];
-    char y[16];
-    DR_state->PrettyUC(aMetrics.Width(), width, 16);
-    DR_state->PrettyUC(aMetrics.Height(), height, 16);
-    printf("Reflow d=%s,%s", width, height);
-
-    if (!aStatus.IsEmpty()) {
-      printf(" status=%s", ToString(aStatus).c_str());
-    }
-    if (aFrame->HasOverflowAreas()) {
-      DR_state->PrettyUC(aMetrics.InkOverflow().x, x, 16);
-      DR_state->PrettyUC(aMetrics.InkOverflow().y, y, 16);
-      DR_state->PrettyUC(aMetrics.InkOverflow().width, width, 16);
-      DR_state->PrettyUC(aMetrics.InkOverflow().height, height, 16);
-      printf(" vis-o=(%s,%s) %s x %s", x, y, width, height);
-
-      nsRect storedOverflow = aFrame->InkOverflowRect();
-      DR_state->PrettyUC(storedOverflow.x, x, 16);
-      DR_state->PrettyUC(storedOverflow.y, y, 16);
-      DR_state->PrettyUC(storedOverflow.width, width, 16);
-      DR_state->PrettyUC(storedOverflow.height, height, 16);
-      printf(" vis-sto=(%s,%s) %s x %s", x, y, width, height);
-
-      DR_state->PrettyUC(aMetrics.ScrollableOverflow().x, x, 16);
-      DR_state->PrettyUC(aMetrics.ScrollableOverflow().y, y, 16);
-      DR_state->PrettyUC(aMetrics.ScrollableOverflow().width, width, 16);
-      DR_state->PrettyUC(aMetrics.ScrollableOverflow().height, height, 16);
-      printf(" scr-o=(%s,%s) %s x %s", x, y, width, height);
-
-      storedOverflow = aFrame->ScrollableOverflowRect();
-      DR_state->PrettyUC(storedOverflow.x, x, 16);
-      DR_state->PrettyUC(storedOverflow.y, y, 16);
-      DR_state->PrettyUC(storedOverflow.width, width, 16);
-      DR_state->PrettyUC(storedOverflow.height, height, 16);
-      printf(" scr-sto=(%s,%s) %s x %s", x, y, width, height);
-    }
-    printf("\n");
-    if (DR_state->mDisplayPixelErrors) {
-      int32_t d2a = aPresContext->AppUnitsPerDevPixel();
-      CheckPixelError(aMetrics.Width(), d2a);
-      CheckPixelError(aMetrics.Height(), d2a);
-    }
-  }
-  DR_state->DeleteTreeNode(*treeNode);
-}
-
-void nsIFrame::DisplayLayoutExit(nsIFrame* aFrame, void* aFrameTreeNode) {
-  if (!DR_state->mActive) return;
-
-  NS_ASSERTION(aFrame, "non-null frame required");
-  if (!aFrameTreeNode) return;
-
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)aFrameTreeNode;
-  if (treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    nsRect rect = aFrame->GetRect();
-    printf("XULLayout=%d,%d,%d,%d\n", rect.x, rect.y, rect.width, rect.height);
-  }
-  DR_state->DeleteTreeNode(*treeNode);
-}
-
-void nsIFrame::DisplayIntrinsicISizeExit(nsIFrame* aFrame, const char* aType,
-                                         nscoord aResult,
-                                         void* aFrameTreeNode) {
-  if (!DR_state->mActive) return;
-
-  NS_ASSERTION(aFrame, "non-null frame required");
-  if (!aFrameTreeNode) return;
-
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)aFrameTreeNode;
-  if (treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    char iSize[16];
-    DR_state->PrettyUC(aResult, iSize, 16);
-    printf("Get%sISize=%s\n", aType, iSize);
-  }
-  DR_state->DeleteTreeNode(*treeNode);
-}
-
-void nsIFrame::DisplayIntrinsicSizeExit(nsIFrame* aFrame, const char* aType,
-                                        nsSize aResult, void* aFrameTreeNode) {
-  if (!DR_state->mActive) return;
-
-  NS_ASSERTION(aFrame, "non-null frame required");
-  if (!aFrameTreeNode) return;
-
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)aFrameTreeNode;
-  if (treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-
-    char width[16];
-    char height[16];
-    DR_state->PrettyUC(aResult.width, width, 16);
-    DR_state->PrettyUC(aResult.height, height, 16);
-    printf("Get%sSize=%s,%s\n", aType, width, height);
-  }
-  DR_state->DeleteTreeNode(*treeNode);
-}
-
-/* static */
-void nsIFrame::DisplayReflowStartup() { DR_state = new DR_State(); }
-
-/* static */
-void nsIFrame::DisplayReflowShutdown() {
-  delete DR_state;
-  DR_state = nullptr;
-}
-
-void DR_cookie::Change() const {
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)mValue;
-  if (treeNode && treeNode->mDisplay) {
-    DisplayReflowEnterPrint(mPresContext, mFrame, mReflowInput, *treeNode,
-                            true);
-  }
-}
-
-/* static */
-void* ReflowInput::DisplayInitConstraintsEnter(nsIFrame* aFrame,
-                                               ReflowInput* aState,
-                                               nscoord aContainingBlockWidth,
-                                               nscoord aContainingBlockHeight,
-                                               const nsMargin* aBorder,
-                                               const nsMargin* aPadding) {
-  MOZ_ASSERT(aFrame, "non-null frame required");
-  MOZ_ASSERT(aState, "non-null state required");
-
-  if (!DR_state->mInited) DR_state->Init();
-  if (!DR_state->mActive) return nullptr;
-
-  DR_FrameTreeNode* treeNode = DR_state->CreateTreeNode(aFrame, aState);
-  if (treeNode && treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-
-    printf("InitConstraints parent=%p", (void*)aState->mParentReflowInput);
-
-    char width[16];
-    char height[16];
-
-    DR_state->PrettyUC(aContainingBlockWidth, width, 16);
-    DR_state->PrettyUC(aContainingBlockHeight, height, 16);
-    printf(" cb=%s,%s", width, height);
-
-    DR_state->PrettyUC(aState->AvailableWidth(), width, 16);
-    DR_state->PrettyUC(aState->AvailableHeight(), height, 16);
-    printf(" as=%s,%s", width, height);
-
-    DR_state->PrintMargin("b", aBorder);
-    DR_state->PrintMargin("p", aPadding);
-    putchar('\n');
-  }
-  return treeNode;
-}
-
-/* static */
-void ReflowInput::DisplayInitConstraintsExit(nsIFrame* aFrame,
-                                             ReflowInput* aState,
-                                             void* aValue) {
-  MOZ_ASSERT(aFrame, "non-null frame required");
-  MOZ_ASSERT(aState, "non-null state required");
-
-  if (!DR_state->mActive) return;
-  if (!aValue) return;
-
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)aValue;
-  if (treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    char cmiw[16], cw[16], cmxw[16], cmih[16], ch[16], cmxh[16];
-    DR_state->PrettyUC(aState->ComputedMinWidth(), cmiw, 16);
-    DR_state->PrettyUC(aState->ComputedWidth(), cw, 16);
-    DR_state->PrettyUC(aState->ComputedMaxWidth(), cmxw, 16);
-    DR_state->PrettyUC(aState->ComputedMinHeight(), cmih, 16);
-    DR_state->PrettyUC(aState->ComputedHeight(), ch, 16);
-    DR_state->PrettyUC(aState->ComputedMaxHeight(), cmxh, 16);
-    printf("InitConstraints= cw=(%s <= %s <= %s) ch=(%s <= %s <= %s)", cmiw, cw,
-           cmxw, cmih, ch, cmxh);
-    const nsMargin m = aState->ComputedPhysicalOffsets();
-    DR_state->PrintMargin("co", &m);
-    putchar('\n');
-  }
-  DR_state->DeleteTreeNode(*treeNode);
-}
-
-/* static */
-void* SizeComputationInput::DisplayInitOffsetsEnter(
-    nsIFrame* aFrame, SizeComputationInput* aState, nscoord aPercentBasis,
-    WritingMode aCBWritingMode, const nsMargin* aBorder,
-    const nsMargin* aPadding) {
-  MOZ_ASSERT(aFrame, "non-null frame required");
-  MOZ_ASSERT(aState, "non-null state required");
-
-  if (!DR_state->mInited) DR_state->Init();
-  if (!DR_state->mActive) return nullptr;
-
-  // aState is not necessarily a ReflowInput
-  DR_FrameTreeNode* treeNode = DR_state->CreateTreeNode(aFrame, nullptr);
-  if (treeNode && treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-
-    char pctBasisStr[16];
-    DR_state->PrettyUC(aPercentBasis, pctBasisStr, 16);
-    printf("InitOffsets pct_basis=%s", pctBasisStr);
-
-    DR_state->PrintMargin("b", aBorder);
-    DR_state->PrintMargin("p", aPadding);
-    putchar('\n');
-  }
-  return treeNode;
-}
-
-/* static */
-void SizeComputationInput::DisplayInitOffsetsExit(nsIFrame* aFrame,
-                                                  SizeComputationInput* aState,
-                                                  void* aValue) {
-  MOZ_ASSERT(aFrame, "non-null frame required");
-  MOZ_ASSERT(aState, "non-null state required");
-
-  if (!DR_state->mActive) return;
-  if (!aValue) return;
-
-  DR_FrameTreeNode* treeNode = (DR_FrameTreeNode*)aValue;
-  if (treeNode->mDisplay) {
-    DR_state->DisplayFrameTypeInfo(aFrame, treeNode->mIndent);
-    printf("InitOffsets=");
-    const auto m = aState->ComputedPhysicalMargin();
-    DR_state->PrintMargin("m", &m);
-    const auto p = aState->ComputedPhysicalPadding();
-    DR_state->PrintMargin("p", &p);
-    const auto bp = aState->ComputedPhysicalBorderPadding();
-    DR_state->PrintMargin("b+p", &bp);
-    putchar('\n');
-  }
-  DR_state->DeleteTreeNode(*treeNode);
-}
-
-// End Display Reflow
-
 // Validation of SideIsVertical.
 #  define CASE(side, result) \
     static_assert(SideIsVertical(side) == result, "SideIsVertical is wrong")
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index 16f3d17d64..6e55ebe1c7 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -937,6 +937,8 @@ class nsIFrame : public nsQueryFrame {
   already_AddRefed<ComputedStyle> ComputeHighlightSelectionStyle(
       nsAtom* aHighlightName);
 
+  already_AddRefed<ComputedStyle> ComputeTargetTextStyle() const;
+
   /**
    * Accessor functions for geometric parent.
    */
@@ -1586,6 +1588,11 @@ class nsIFrame : public nsQueryFrame {
   bool GetShapeBoxBorderRadii(nscoord aRadii[8]) const;
 
   /**
+   * Returns one em unit, adjusted for font inflation if needed, in app units.
+   */
+  nscoord OneEmInAppUnits() const;
+
+  /**
    * `GetNaturalBaselineBOffset`, but determines the baseline sharing group
    * through `GetDefaultBaselineSharingGroup` (If not specified), assuming line
    * layout context, and never fails, returning a synthesized baseline through
@@ -3932,6 +3939,9 @@ class nsIFrame : public nsQueryFrame {
  public:
   // given a frame five me the first/last leaf available
   // XXX Robert O'Callahan wants to move these elsewhere
+  // FIXME: Only GetLastLeaf() never returns a leaf frame in native anonymous
+  // subtrees under aFrame.  However, GetFirstLeaf() may return a leaf frame
+  // in a native anonymous subtree.
   static void GetLastLeaf(nsIFrame** aFrame);
   static void GetFirstLeaf(nsIFrame** aFrame);
 
@@ -5482,25 +5492,6 @@ class nsIFrame : public nsQueryFrame {
   // NS_FRAME_IS_DIRTY bit set
   static void VerifyDirtyBitSet(const nsFrameList& aFrameList);
 
-  // Display Reflow Debugging
-  static void* DisplayReflowEnter(nsPresContext* aPresContext, nsIFrame* aFrame,
-                                  const ReflowInput& aReflowInput);
-  static void* DisplayLayoutEnter(nsIFrame* aFrame);
-  static void* DisplayIntrinsicISizeEnter(nsIFrame* aFrame, const char* aType);
-  static void* DisplayIntrinsicSizeEnter(nsIFrame* aFrame, const char* aType);
-  static void DisplayReflowExit(nsPresContext* aPresContext, nsIFrame* aFrame,
-                                ReflowOutput& aMetrics,
-                                const nsReflowStatus& aStatus,
-                                void* aFrameTreeNode);
-  static void DisplayLayoutExit(nsIFrame* aFrame, void* aFrameTreeNode);
-  static void DisplayIntrinsicISizeExit(nsIFrame* aFrame, const char* aType,
-                                        nscoord aResult, void* aFrameTreeNode);
-  static void DisplayIntrinsicSizeExit(nsIFrame* aFrame, const char* aType,
-                                       nsSize aResult, void* aFrameTreeNode);
-
-  static void DisplayReflowStartup();
-  static void DisplayReflowShutdown();
-
   static mozilla::LazyLogModule sFrameLogModule;
 #endif
 };
diff --git a/layout/generic/nsIFrameInlines.h b/layout/generic/nsIFrameInlines.h
index e187f0dfb0..f53ba607c0 100644
--- a/layout/generic/nsIFrameInlines.h
+++ b/layout/generic/nsIFrameInlines.h
@@ -36,7 +36,7 @@ bool nsIFrame::IsFlexOrGridItem() const {
 
 bool nsIFrame::IsMasonry(mozilla::LogicalAxis aAxis) const {
   MOZ_DIAGNOSTIC_ASSERT(IsGridContainerFrame());
-  return HasAnyStateBits(aAxis == mozilla::eLogicalAxisBlock
+  return HasAnyStateBits(aAxis == mozilla::LogicalAxis::Block
                              ? NS_STATE_GRID_IS_ROW_MASONRY
                              : NS_STATE_GRID_IS_COL_MASONRY);
 }
diff --git a/layout/generic/nsImageFrame.cpp b/layout/generic/nsImageFrame.cpp
index c1e69df6c9..91d8430b60 100644
--- a/layout/generic/nsImageFrame.cpp
+++ b/layout/generic/nsImageFrame.cpp
@@ -1476,8 +1476,6 @@ nscoord nsImageFrame::GetContinuationOffset() const {
 nscoord nsImageFrame::GetMinISize(gfxContext* aRenderingContext) {
   // XXX The caller doesn't account for constraints of the block-size,
   // min-block-size, and max-block-size properties.
-  DebugOnly<nscoord> result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
   EnsureIntrinsicSizeAndRatio();
   const auto& iSize = GetWritingMode().IsVertical() ? mIntrinsicSize.height
                                                     : mIntrinsicSize.width;
@@ -1487,8 +1485,6 @@ nscoord nsImageFrame::GetMinISize(gfxContext* aRenderingContext) {
 nscoord nsImageFrame::GetPrefISize(gfxContext* aRenderingContext) {
   // XXX The caller doesn't account for constraints of the block-size,
   // min-block-size, and max-block-size properties.
-  DebugOnly<nscoord> result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
   EnsureIntrinsicSizeAndRatio();
   const auto& iSize = GetWritingMode().IsVertical() ? mIntrinsicSize.height
                                                     : mIntrinsicSize.width;
@@ -1526,7 +1522,6 @@ void nsImageFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                           nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsImageFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
diff --git a/layout/generic/nsInlineFrame.cpp b/layout/generic/nsInlineFrame.cpp
index 7a99ecbe5d..b481c71827 100644
--- a/layout/generic/nsInlineFrame.cpp
+++ b/layout/generic/nsInlineFrame.cpp
@@ -270,7 +270,6 @@ void nsInlineFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                            nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsInlineFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   if (!aReflowInput.mLineLayout) {
diff --git a/layout/generic/nsLeafFrame.cpp b/layout/generic/nsLeafFrame.cpp
index 2688da3d4b..6125f6b800 100644
--- a/layout/generic/nsLeafFrame.cpp
+++ b/layout/generic/nsLeafFrame.cpp
@@ -24,18 +24,12 @@ void nsLeafFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
 
 /* virtual */
 nscoord nsLeafFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  result = GetIntrinsicISize();
-  return result;
+  return GetIntrinsicISize();
 }
 
 /* virtual */
 nscoord nsLeafFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  result = GetIntrinsicISize();
-  return result;
+  return GetIntrinsicISize();
 }
 
 /* virtual */
diff --git a/layout/generic/nsLineBox.cpp b/layout/generic/nsLineBox.cpp
index 18051aa69a..53a6914030 100644
--- a/layout/generic/nsLineBox.cpp
+++ b/layout/generic/nsLineBox.cpp
@@ -217,7 +217,7 @@ void nsLineBox::List(FILE* out, const char* aPrefix,
       IsPreviousMarginDirty() ? "prevmargindirty" : "prevmarginclean",
       IsImpactedByFloat() ? "impacted" : "not-impacted",
       IsLineWrapped() ? "wrapped" : "not-wrapped",
-      HasForcedLineBreak() ? "forced-break" : "no-break",
+      HasForcedLineBreakAfter() ? "forced-break-after" : "no-break",
       StyleClearToString(FloatClearTypeBefore()),
       StyleClearToString(FloatClearTypeAfter()));
 
diff --git a/layout/generic/nsLineBox.h b/layout/generic/nsLineBox.h
index d46cf9604a..e35f36a481 100644
--- a/layout/generic/nsLineBox.h
+++ b/layout/generic/nsLineBox.h
@@ -238,42 +238,40 @@ class nsLineBox final : public nsLineLink {
     }
   }
 
-  // mHasForcedLineBreak bit & mFloatClearType value
-  // Break information is applied *before* the line if the line is a block,
-  // or *after* the line if the line is an inline.
-  bool HasForcedLineBreak() const { return mFlags.mHasForcedLineBreak; }
+  // mHasForcedLineBreakAfter bit & mFloatClearType value
   void ClearForcedLineBreak() {
-    mFlags.mHasForcedLineBreak = false;
+    mFlags.mHasForcedLineBreakAfter = false;
     mFlags.mFloatClearType = mozilla::StyleClear::None;
   }
 
-  bool HasForcedLineBreakBefore() const {
-    return IsBlock() && HasForcedLineBreak();
+  bool HasFloatClearTypeBefore() const {
+    return FloatClearTypeBefore() != mozilla::StyleClear::None;
   }
-  void SetForcedLineBreakBefore(mozilla::StyleClear aClearType) {
-    MOZ_ASSERT(IsBlock(), "Only blocks have break-before");
+  void SetFloatClearTypeBefore(mozilla::StyleClear aClearType) {
+    MOZ_ASSERT(IsBlock(), "Only block lines have break-before status!");
     MOZ_ASSERT(aClearType != mozilla::StyleClear::None,
                "Only StyleClear:Left/Right/Both are allowed before a line");
-    mFlags.mHasForcedLineBreak = true;
     mFlags.mFloatClearType = aClearType;
   }
   mozilla::StyleClear FloatClearTypeBefore() const {
-    return IsBlock() ? FloatClearType() : mozilla::StyleClear::None;
+    return IsBlock() ? mFlags.mFloatClearType : mozilla::StyleClear::None;
   }
 
   bool HasForcedLineBreakAfter() const {
-    return IsInline() && HasForcedLineBreak();
+    MOZ_ASSERT(IsInline() || !mFlags.mHasForcedLineBreakAfter,
+               "A block line shouldn't set mHasForcedLineBreakAfter bit!");
+    return IsInline() && mFlags.mHasForcedLineBreakAfter;
   }
   void SetForcedLineBreakAfter(mozilla::StyleClear aClearType) {
-    MOZ_ASSERT(IsInline(), "Only inlines have break-after");
-    mFlags.mHasForcedLineBreak = true;
+    MOZ_ASSERT(IsInline(), "Only inline lines have break-after status!");
+    mFlags.mHasForcedLineBreakAfter = true;
     mFlags.mFloatClearType = aClearType;
   }
   bool HasFloatClearTypeAfter() const {
-    return IsInline() && FloatClearType() != mozilla::StyleClear::None;
+    return FloatClearTypeAfter() != mozilla::StyleClear::None;
   }
   mozilla::StyleClear FloatClearTypeAfter() const {
-    return IsInline() ? FloatClearType() : mozilla::StyleClear::None;
+    return IsInline() ? mFlags.mFloatClearType : mozilla::StyleClear::None;
   }
 
   // mCarriedOutBEndMargin value
@@ -316,7 +314,7 @@ class nsLineBox final : public nsLineLink {
   nsRect InkOverflowRect() const {
     return GetOverflowArea(mozilla::OverflowType::Ink);
   }
-  nsRect ScrollableOverflowRect() {
+  nsRect ScrollableOverflowRect() const {
     return GetOverflowArea(mozilla::OverflowType::Scrollable);
   }
 
@@ -520,11 +518,15 @@ class nsLineBox final : public nsLineLink {
     // Has this line moved to a different fragment of the block since
     // the last time it was reflowed?
     bool mMovedFragments : 1;
-    // mHasForcedLineBreak indicates that this line has either a break-before or
-    // a break-after.
-    bool mHasForcedLineBreak : 1;
-    // mFloatClearType indicates that there's a float clearance before or after
-    // this line.
+    // mHasForcedLineBreakAfter indicates that this *inline* line has a
+    // break-after status due to a float clearance or ending with <br>. A block
+    // line shouldn't set this bit.
+    //
+    // Note: This bit is unrelated to CSS break-after property because it is all
+    // about line break-after for inline-level boxes.
+    bool mHasForcedLineBreakAfter : 1;
+    // mFloatClearType indicates that there's a float clearance before a block
+    // line, or after an inline line.
     mozilla::StyleClear mFloatClearType;
   };
 
@@ -570,8 +572,6 @@ class nsLineBox final : public nsLineLink {
     FlagBits mFlags;
   };
 
-  mozilla::StyleClear FloatClearType() const { return mFlags.mFloatClearType; };
-
   union {
     ExtraData* mData;
     ExtraBlockData* mBlockData;
diff --git a/layout/generic/nsLineLayout.cpp b/layout/generic/nsLineLayout.cpp
index ab6924faa4..be6f64f1fe 100644
--- a/layout/generic/nsLineLayout.cpp
+++ b/layout/generic/nsLineLayout.cpp
@@ -1713,10 +1713,10 @@ void nsLineLayout::AdjustLeadings(nsIFrame* spanFrame, PerSpanData* psd,
   if (aStyleText->HasEffectiveTextEmphasis()) {
     nscoord bsize = GetBSizeOfEmphasisMarks(spanFrame, aInflation);
     LogicalSide side = aStyleText->TextEmphasisSide(mRootSpan->mWritingMode);
-    if (side == eLogicalSideBStart) {
+    if (side == LogicalSide::BStart) {
       requiredStartLeading += bsize;
     } else {
-      MOZ_ASSERT(side == eLogicalSideBEnd,
+      MOZ_ASSERT(side == LogicalSide::BEnd,
                  "emphasis marks must be in block axis");
       requiredEndLeading += bsize;
     }
@@ -2341,7 +2341,7 @@ void nsLineLayout::VerticalAlignFrames(PerSpanData* psd) {
               delta = emphasisHeight;
             }
             LogicalSide side = mStyleText->TextEmphasisSide(lineWM);
-            if (side == eLogicalSideBStart) {
+            if (side == LogicalSide::BStart) {
               blockStart -= delta;
             } else {
               blockEnd += delta;
diff --git a/layout/generic/nsPageContentFrame.cpp b/layout/generic/nsPageContentFrame.cpp
index 11e634894d..1c82ca1523 100644
--- a/layout/generic/nsPageContentFrame.cpp
+++ b/layout/generic/nsPageContentFrame.cpp
@@ -35,7 +35,6 @@ void nsPageContentFrame::Reflow(nsPresContext* aPresContext,
                                 nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsPageContentFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   MOZ_ASSERT(mPD, "Need a pointer to nsSharedPageData before reflow starts");
 
diff --git a/layout/generic/nsPageFrame.cpp b/layout/generic/nsPageFrame.cpp
index fb9cfa2e81..de573962af 100644
--- a/layout/generic/nsPageFrame.cpp
+++ b/layout/generic/nsPageFrame.cpp
@@ -9,6 +9,7 @@
 #include "mozilla/AppUnits.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/StaticPrefs_print.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/intl/Segmenter.h"
 #include "gfxContext.h"
@@ -213,7 +214,6 @@ void nsPageFrame::Reflow(nsPresContext* aPresContext,
                          nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsPageFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   MOZ_ASSERT(mPD, "Need a pointer to nsSharedPageData before reflow starts");
 
@@ -540,6 +540,69 @@ static std::tuple<uint32_t, uint32_t> GetRowAndColFromIdx(uint32_t aIdxOnSheet,
   return {aIdxOnSheet / aNumCols, aIdxOnSheet % aNumCols};
 }
 
+// The minimum ratio for which we will center the page on the sheet when using
+// auto-detect logic.
+// Note that this ratio is of the content's size to the sheet size scaled to be
+// in content space, and so the actual ratio will always be from 0.0 to 1.0,
+// with this marking the smallest ratio we consider a near-miss.
+// The ratio of A4 on Letter is 0.915034. A threshold of 0.9 will ensure that
+// A4 on Letter works, as well as other near-misses.
+//
+// The ratio is computed as so:
+// scale = min(1, sheetHeight / pageHeight, sheetWidth / pageWidth)
+//
+// Where pageSize is pageWidth or pageHeight, and sheetSize is sheetWidth or
+// sheetHeight, respectively:
+// scaledPageSize = pageSize * scale
+// ratio = scaledPageSize / sheetSize
+//
+// A4 (210mm x 297mm) on US Letter (215.9mm x 279.4mm) is derived as so:
+// scale = min(1, 215.9 / 210, 279.4 / 297) = 0.9407407407..
+//
+// Using the widths:
+// scaledPageSize = (210 * 0.940741) = 197.556
+// ratio = 197.556 / 215.9 = 0.915034
+//
+// See nsPageFrame::ComputeSinglePPSPageSizeScale for scale calculation, and
+// OffsetToCenterPage for ratio calculation.
+constexpr float kCenterPageRatioThreshold = 0.9f;
+
+// Numeric values for the pref "print.center_page_on_sheet"
+enum {
+  kPrintCenterPageOnSheetNever = 0,
+  kPrintCenterPageOnSheetAlways = 1,
+  kPrintCenterPageOnSheetAuto = 2
+};
+
+// Returns an offset to center the page on the sheet, with a given scale.
+// When no centering can/should happen, this will avoid extra calculations and
+// return 0.0f.
+// This takes into account the value of the pref "print.center_page_on_sheet".
+static float OffsetToCenterPage(nscoord aContentSize, nscoord aSheetSize,
+                                float aScale, float aAppUnitsPerPixel) {
+  MOZ_ASSERT(aScale <= 1.0f && aScale > 0.0f,
+             "Scale must be in the range (0,1]");
+  const unsigned centerPagePref = StaticPrefs::print_center_page_on_sheet();
+  if (centerPagePref == kPrintCenterPageOnSheetNever) {
+    return 0.0f;
+  }
+
+  // Determine the ratio of scaled page to the sheet size.
+  const float sheetSize =
+      NSAppUnitsToFloatPixels(aSheetSize, aAppUnitsPerPixel);
+  const float scaledContentSize =
+      NSAppUnitsToFloatPixels(aContentSize, aAppUnitsPerPixel) * aScale;
+  const float ratio = scaledContentSize / sheetSize;
+
+  // If the ratio is within the threshold, or the pref indicates we should
+  // always center the page, return half the difference to form the offset.
+  if (centerPagePref == kPrintCenterPageOnSheetAlways ||
+      ratio >= kCenterPageRatioThreshold) {
+    return (sheetSize - scaledContentSize) * 0.5f;
+  }
+  return 0.0f;
+}
+
 // Helper for BuildDisplayList:
 static gfx::Matrix4x4 ComputePagesPerSheetAndPageSizeTransform(
     const nsIFrame* aFrame, float aAppUnitsPerPixel) {
@@ -561,8 +624,8 @@ static gfx::Matrix4x4 ComputePagesPerSheetAndPageSizeTransform(
   gfx::Matrix4x4 transform;
 
   if (ppsInfo->mNumPages == 1) {
+    const nsSize sheetSize = sheetFrame->GetSizeForChildren();
     if (rotation != 0.0) {
-      const nsSize sheetSize = sheetFrame->GetSizeForChildren();
       const bool sheetIsPortrait = sheetSize.width < sheetSize.height;
       const bool rotatingClockwise = rotation > 0.0;
 
@@ -584,7 +647,21 @@ static gfx::Matrix4x4 ComputePagesPerSheetAndPageSizeTransform(
                              NSAppUnitsToFloatPixels(-y, aAppUnitsPerPixel), 0);
     }
 
-    float scale = pageFrame->ComputeSinglePPSPageSizeScale(contentPageSize);
+    // If the difference in horizontal size, after scaling, is relatively small
+    // then center the page on the sheet.
+    const float scale =
+        pageFrame->ComputeSinglePPSPageSizeScale(contentPageSize);
+    const float centeringOffset = OffsetToCenterPage(
+        contentPageSize.width, sheetSize.width, scale, aAppUnitsPerPixel);
+
+    // Only bother with the translation if it is at least one pixel.
+    // It's possible for a mismatch in the paper size reported by the print
+    // server and the paper size from Gecko to lead to small offsets, or
+    // even (in combination with floating point error) a very small negative
+    // offset. Do not apply an offset in those cases.
+    if (centeringOffset >= 1.0f) {
+      transform.PreTranslate(centeringOffset, 0, 0);
+    }
     transform.PreScale(scale, scale, 1);
     return transform;
   }
@@ -937,7 +1014,6 @@ void nsPageBreakFrame::Reflow(nsPresContext* aPresContext,
                               const ReflowInput& aReflowInput,
                               nsReflowStatus& aStatus) {
   DO_GLOBAL_REFLOW_COUNT("nsPageBreakFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Override reflow, since we don't want to deal with what our
diff --git a/layout/generic/nsPageSequenceFrame.cpp b/layout/generic/nsPageSequenceFrame.cpp
index a3348433cb..cd3c2cd6a5 100644
--- a/layout/generic/nsPageSequenceFrame.cpp
+++ b/layout/generic/nsPageSequenceFrame.cpp
@@ -266,7 +266,6 @@ void nsPageSequenceFrame::Reflow(nsPresContext* aPresContext,
   MOZ_ASSERT(aPresContext->IsRootPaginatedDocument(),
              "A Page Sequence is only for real pages");
   DO_GLOBAL_REFLOW_COUNT("nsPageSequenceFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aReflowOutput, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE_REFLOW_IN("nsPageSequenceFrame::Reflow");
 
diff --git a/layout/generic/nsPlaceholderFrame.cpp b/layout/generic/nsPlaceholderFrame.cpp
index f6b4d53193..aad2c816e5 100644
--- a/layout/generic/nsPlaceholderFrame.cpp
+++ b/layout/generic/nsPlaceholderFrame.cpp
@@ -124,7 +124,6 @@ void nsPlaceholderFrame::Reflow(nsPresContext* aPresContext,
 
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsPlaceholderFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   aDesiredSize.ClearSize();
 }
diff --git a/layout/generic/nsRubyBaseContainerFrame.cpp b/layout/generic/nsRubyBaseContainerFrame.cpp
index 6e29152bc9..50b08b6f5b 100644
--- a/layout/generic/nsRubyBaseContainerFrame.cpp
+++ b/layout/generic/nsRubyBaseContainerFrame.cpp
@@ -275,7 +275,6 @@ void nsRubyBaseContainerFrame::Reflow(nsPresContext* aPresContext,
                                       nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsRubyBaseContainerFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   if (!aReflowInput.mLineLayout) {
diff --git a/layout/generic/nsRubyFrame.cpp b/layout/generic/nsRubyFrame.cpp
index d7da5bc321..d6119f44fb 100644
--- a/layout/generic/nsRubyFrame.cpp
+++ b/layout/generic/nsRubyFrame.cpp
@@ -94,7 +94,6 @@ void nsRubyFrame::Reflow(nsPresContext* aPresContext,
                          nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsRubyFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   if (!aReflowInput.mLineLayout) {
@@ -345,11 +344,11 @@ void nsRubyFrame::ReflowSegment(nsPresContext* aPresContext,
                 : 0);
         position = offsetRect.Origin(lineWM) + offset;
         aReflowInput.mLineLayout->AdvanceICoord(size.ISize(lineWM));
-      } else if (logicalSide == eLogicalSideBStart) {
+      } else if (logicalSide == LogicalSide::BStart) {
         offsetRect.BStart(lineWM) -= size.BSize(lineWM);
         offsetRect.BSize(lineWM) += size.BSize(lineWM);
         position = offsetRect.Origin(lineWM);
-      } else if (logicalSide == eLogicalSideBEnd) {
+      } else if (logicalSide == LogicalSide::BEnd) {
         position = offsetRect.Origin(lineWM) +
                    LogicalPoint(lineWM, 0, offsetRect.BSize(lineWM));
         offsetRect.BSize(lineWM) += size.BSize(lineWM);
diff --git a/layout/generic/nsRubyTextContainerFrame.cpp b/layout/generic/nsRubyTextContainerFrame.cpp
index 855d7c1825..8494b36a28 100644
--- a/layout/generic/nsRubyTextContainerFrame.cpp
+++ b/layout/generic/nsRubyTextContainerFrame.cpp
@@ -105,7 +105,6 @@ void nsRubyTextContainerFrame::Reflow(nsPresContext* aPresContext,
                                       nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsRubyTextContainerFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Although a ruby text container may have continuations, returning
diff --git a/layout/generic/nsSubDocumentFrame.cpp b/layout/generic/nsSubDocumentFrame.cpp
index bfbd7763a9..69b4042033 100644
--- a/layout/generic/nsSubDocumentFrame.cpp
+++ b/layout/generic/nsSubDocumentFrame.cpp
@@ -555,7 +555,6 @@ nsresult nsSubDocumentFrame::GetFrameName(nsAString& aResult) const {
 /* virtual */
 nscoord nsSubDocumentFrame::GetMinISize(gfxContext* aRenderingContext) {
   nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
 
   nsCOMPtr<nsIObjectLoadingContent> iolc = do_QueryInterface(mContent);
   auto olc = static_cast<nsObjectLoadingContent*>(iolc.get());
@@ -575,18 +574,13 @@ nscoord nsSubDocumentFrame::GetMinISize(gfxContext* aRenderingContext) {
 
 /* virtual */
 nscoord nsSubDocumentFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
   // If the subdocument is an SVG document, then in theory we want to return
   // the same thing that SVGOuterSVGFrame::GetPrefISize does.  That method
   // has some special handling of percentage values to avoid unhelpful zero
   // sizing in the presence of orthogonal writing modes.  We don't bother
   // with that for SVG documents in <embed> and <object>, since that special
   // handling doesn't look up across document boundaries anyway.
-  result = GetIntrinsicISize();
-
-  return result;
+  return GetIntrinsicISize();
 }
 
 /* virtual */
@@ -676,7 +670,6 @@ void nsSubDocumentFrame::Reflow(nsPresContext* aPresContext,
                                 nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsSubDocumentFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 9afefc5c28..0ad527e842 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -1929,8 +1929,8 @@ bool BuildTextRunsScanner::ContinueTextRunAcrossFrames(nsTextFrame* aFrame1,
 
     // Map inline-end and inline-start to physical sides for checking presence
     // of non-zero margin/border/padding.
-    Side side1 = wm.PhysicalSide(eLogicalSideIEnd);
-    Side side2 = wm.PhysicalSide(eLogicalSideIStart);
+    Side side1 = wm.PhysicalSide(LogicalSide::IEnd);
+    Side side2 = wm.PhysicalSide(LogicalSide::IStart);
     // If the frames have an embedding level that is opposite to the writing
     // mode, we need to swap which sides we're checking.
     if (aFrame1->GetEmbeddingLevel().IsRTL() == wm.IsBidiLTR()) {
@@ -3611,6 +3611,20 @@ void nsTextFrame::PropertyProvider::GetSpacing(Range aRange,
       !(mTextRun->GetFlags2() & nsTextFrameUtils::Flags::HasTab));
 }
 
+static bool CanAddSpacingBefore(const gfxTextRun* aTextRun, uint32_t aOffset,
+                                bool aNewlineIsSignificant) {
+  const auto* g = aTextRun->GetCharacterGlyphs();
+  MOZ_ASSERT(aOffset < aTextRun->GetLength());
+  if (aNewlineIsSignificant && g[aOffset].CharIsNewline()) {
+    return false;
+  }
+  if (!aOffset) {
+    return true;
+  }
+  return g[aOffset].IsClusterStart() && g[aOffset].IsLigatureGroupStart() &&
+         !g[aOffset - 1].CharIsFormattingControl() && !g[aOffset].CharIsTab();
+}
+
 static bool CanAddSpacingAfter(const gfxTextRun* aTextRun, uint32_t aOffset,
                                bool aNewlineIsSignificant) {
   const auto* g = aTextRun->GetCharacterGlyphs();
@@ -3683,14 +3697,45 @@ void nsTextFrame::PropertyProvider::GetSpacingInternal(Range aRange,
     nsSkipCharsRunIterator run(
         start, nsSkipCharsRunIterator::LENGTH_UNSKIPPED_ONLY, aRange.Length());
     bool newlineIsSignificant = mTextStyle->NewlineIsSignificant(mFrame);
+    // Which letter-spacing model are we using?
+    //   0 - Gecko legacy model, spacing added to trailing side of letter
+    //   1 - WebKit/Blink-compatible, spacing added to right-hand side
+    //   2 - Symmetrical spacing, half added to each side
+    gfxFloat before, after;
+    switch (StaticPrefs::layout_css_letter_spacing_model()) {
+      default:  // use Gecko legacy behavior if pref value is unknown
+      case 0:
+        before = 0.0;
+        after = mLetterSpacing;
+        break;
+      case 1:
+        if (mTextRun->IsRightToLeft()) {
+          before = mLetterSpacing;
+          after = 0.0;
+        } else {
+          before = 0.0;
+          after = mLetterSpacing;
+        }
+        break;
+      case 2:
+        before = mLetterSpacing / 2.0;
+        after = mLetterSpacing - before;
+        break;
+    }
     while (run.NextRun()) {
       uint32_t runOffsetInSubstring = run.GetSkippedOffset() - aRange.start;
       gfxSkipCharsIterator iter = run.GetPos();
       for (int32_t i = 0; i < run.GetRunLength(); ++i) {
-        if (CanAddSpacingAfter(mTextRun, run.GetSkippedOffset() + i,
+        if (before != 0.0 &&
+            CanAddSpacingBefore(mTextRun, run.GetSkippedOffset() + i,
+                                newlineIsSignificant)) {
+          aSpacing[runOffsetInSubstring + i].mBefore += before;
+        }
+        if (after != 0.0 &&
+            CanAddSpacingAfter(mTextRun, run.GetSkippedOffset() + i,
                                newlineIsSignificant)) {
           // End of a cluster, not in a ligature: put letter-spacing after it
-          aSpacing[runOffsetInSubstring + i].mAfter += mLetterSpacing;
+          aSpacing[runOffsetInSubstring + i].mAfter += after;
         }
         if (IsCSSWordSpacingSpace(mFrag, i + run.GetOriginalOffset(), mFrame,
                                   mTextStyle)) {
@@ -5050,25 +5095,25 @@ nsRect nsTextFrame::UpdateTextEmphasis(WritingMode aWM,
           : do_AddRef(aProvider.GetFontMetrics());
   // When the writing mode is vertical-lr the line is inverted, and thus
   // the ascent and descent are swapped.
-  nscoord absOffset = (side == eLogicalSideBStart) != aWM.IsLineInverted()
+  nscoord absOffset = (side == LogicalSide::BStart) != aWM.IsLineInverted()
                           ? baseFontMetrics->MaxAscent() + fm->MaxDescent()
                           : baseFontMetrics->MaxDescent() + fm->MaxAscent();
   RubyBlockLeadings leadings;
   if (nsRubyFrame* ruby = FindFurthestInlineRubyAncestor(this)) {
     leadings = ruby->GetBlockLeadings();
   }
-  if (side == eLogicalSideBStart) {
+  if (side == LogicalSide::BStart) {
     info->baselineOffset = -absOffset - leadings.mStart;
     overflowRect.BStart(aWM) = -overflowRect.BSize(aWM) - leadings.mStart;
   } else {
-    MOZ_ASSERT(side == eLogicalSideBEnd);
+    MOZ_ASSERT(side == LogicalSide::BEnd);
     info->baselineOffset = absOffset + leadings.mEnd;
     overflowRect.BStart(aWM) = frameSize.BSize(aWM) + leadings.mEnd;
   }
   // If text combined, fix the gap between the text frame and its parent.
   if (isTextCombined) {
     nscoord gap = (baseFontMetrics->MaxHeight() - frameSize.BSize(aWM)) / 2;
-    overflowRect.BStart(aWM) += gap * (side == eLogicalSideBStart ? -1 : 1);
+    overflowRect.BStart(aWM) += gap * (side == LogicalSide::BStart ? -1 : 1);
   }
 
   SetProperty(EmphasisMarkProperty(), info);
@@ -5676,6 +5721,10 @@ bool nsTextFrame::GetSelectionTextColors(SelectionType aSelectionType,
           aHighlightName, aBackground);
       return hasForeground || hasBackground;
     }
+    case SelectionType::eTargetText: {
+      aTextPaintStyle.GetTargetTextColors(aForeground, aBackground);
+      return true;
+    }
     case SelectionType::eURLSecondary:
       aTextPaintStyle.GetURLSecondaryColor(aForeground);
       *aBackground = NS_RGBA(0, 0, 0, 0);
@@ -9216,7 +9265,6 @@ void nsTextFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                          nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTextFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   InvalidateSelectionState();
diff --git a/layout/generic/nsTextPaintStyle.cpp b/layout/generic/nsTextPaintStyle.cpp
index e97a059b07..f29fa753d0 100644
--- a/layout/generic/nsTextPaintStyle.cpp
+++ b/layout/generic/nsTextPaintStyle.cpp
@@ -213,6 +213,24 @@ void nsTextPaintStyle::GetHighlightColors(nscolor* aForeColor,
   *aBackColor = NS_TRANSPARENT;
 }
 
+void nsTextPaintStyle::GetTargetTextColors(nscolor* aForeColor,
+                                           nscolor* aBackColor) {
+  NS_ASSERTION(aForeColor, "aForeColor is null");
+  NS_ASSERTION(aBackColor, "aBackColor is null");
+  const RefPtr<const ComputedStyle> targetTextStyle =
+      mFrame->ComputeTargetTextStyle();
+  if (targetTextStyle) {
+    *aForeColor = targetTextStyle->GetVisitedDependentColor(
+        &nsStyleText::mWebkitTextFillColor);
+    *aBackColor = targetTextStyle->GetVisitedDependentColor(
+        &nsStyleBackground::mBackgroundColor);
+    return;
+  }
+  // XXX(:jjaschke): Before shipping this feature, a sensible set of colors must
+  // be set (Bug 1867940).
+  // in the meantime, use the colors of find selection.
+  GetHighlightColors(aForeColor, aBackColor);
+}
 bool nsTextPaintStyle::GetCustomHighlightTextColor(nsAtom* aHighlightName,
                                                    nscolor* aForeColor) {
   NS_ASSERTION(aForeColor, "aForeColor is null");
diff --git a/layout/generic/nsTextPaintStyle.h b/layout/generic/nsTextPaintStyle.h
index adf28fdad8..94cd3cf322 100644
--- a/layout/generic/nsTextPaintStyle.h
+++ b/layout/generic/nsTextPaintStyle.h
@@ -65,6 +65,7 @@ class MOZ_STACK_CLASS nsTextPaintStyle {
    */
   bool GetSelectionColors(nscolor* aForeColor, nscolor* aBackColor);
   void GetHighlightColors(nscolor* aForeColor, nscolor* aBackColor);
+  void GetTargetTextColors(nscolor* aForeColor, nscolor* aBackColor);
   // Computes colors for custom highlights.
   // Returns false if there are no rules associated with `aHighlightName`.
   bool GetCustomHighlightTextColor(nsAtom* aHighlightName, nscolor* aForeColor);
diff --git a/layout/generic/nsTextRunTransformations.cpp b/layout/generic/nsTextRunTransformations.cpp
index d18a7ec293..de9fd31fda 100644
--- a/layout/generic/nsTextRunTransformations.cpp
+++ b/layout/generic/nsTextRunTransformations.cpp
@@ -80,6 +80,26 @@ bool nsTransformedTextRun::SetPotentialLineBreaks(Range aRange,
   return changed;
 }
 
+void nsTransformedTextRun::SetEmergencyWrapPositions() {
+  // This parallels part of what gfxShapedText::SetupClusterBoundaries() does
+  // for normal textruns.
+  bool prevWasHyphen = false;
+  for (uint32_t pos : IntegerRange(mString.Length())) {
+    const char16_t ch = mString[pos];
+    if (prevWasHyphen) {
+      if (nsContentUtils::IsAlphanumeric(ch)) {
+        mCharacterGlyphs[pos].SetCanBreakBefore(
+            CompressedGlyph::FLAG_BREAK_TYPE_EMERGENCY_WRAP);
+      }
+      prevWasHyphen = false;
+    }
+    if (nsContentUtils::IsHyphen(ch) && pos &&
+        nsContentUtils::IsAlphanumeric(mString[pos - 1])) {
+      prevWasHyphen = true;
+    }
+  }
+}
+
 size_t nsTransformedTextRun::SizeOfExcludingThis(
     mozilla::MallocSizeOf aMallocSizeOf) {
   size_t total = gfxTextRun::SizeOfExcludingThis(aMallocSizeOf);
diff --git a/layout/generic/nsTextRunTransformations.h b/layout/generic/nsTextRunTransformations.h
index 915211c6af..6bcf26a8c0 100644
--- a/layout/generic/nsTextRunTransformations.h
+++ b/layout/generic/nsTextRunTransformations.h
@@ -202,7 +202,10 @@ class nsTransformedTextRun final : public gfxTextRun {
         mOwnsFactory(aOwnsFactory),
         mNeedsRebuild(true) {
     mCharacterGlyphs = reinterpret_cast<CompressedGlyph*>(this + 1);
+    SetEmergencyWrapPositions();
   }
+
+  void SetEmergencyWrapPositions();
 };
 
 /**
diff --git a/layout/generic/nsVideoFrame.cpp b/layout/generic/nsVideoFrame.cpp
index d5bcc45969..e003058c3e 100644
--- a/layout/generic/nsVideoFrame.cpp
+++ b/layout/generic/nsVideoFrame.cpp
@@ -226,7 +226,6 @@ void nsVideoFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                           nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsVideoFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
@@ -375,14 +374,9 @@ nsIFrame::SizeComputationResult nsVideoFrame::ComputeSize(
 }
 
 nscoord nsVideoFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  // Bind the result variable to a RAII-based debug object - the variable
-  // therefore must match the function's return value.
-  DISPLAY_MIN_INLINE_SIZE(this, result);
   // This call handles size-containment
   nsSize size = GetIntrinsicSize().ToSize().valueOr(nsSize());
-  result = GetWritingMode().IsVertical() ? size.height : size.width;
-  return result;
+  return GetWritingMode().IsVertical() ? size.height : size.width;
 }
 
 nscoord nsVideoFrame::GetPrefISize(gfxContext* aRenderingContext) {
diff --git a/layout/generic/test/mochitest.toml b/layout/generic/test/mochitest.toml
index 5c06c90eb7..dcaac3de7a 100644
--- a/layout/generic/test/mochitest.toml
+++ b/layout/generic/test/mochitest.toml
@@ -12,6 +12,7 @@ support-files = [
   "file_SlowTallImage.sjs",
   "bug1174521.html",
   "!/gfx/layers/apz/test/mochitest/apz_test_utils.js",
+  "selection_cross_shadow_boundary_helper.js",
 ]
 
 ["test_bug240933.html"]
@@ -265,6 +266,42 @@ support-files = [
 
 ["test_selection_changes_with_middle_mouse_button.html"]
 
+["test_selection_cross_shadow_boundary_1_backward_click.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_1_backward_drag.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_1_forward_click.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_1_forward_drag.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_2_backward_click.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_2_backward_drag.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_2_forward_click.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_2_forward_drag.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_multi_ranges_forward_drag.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_multi_ranges_forward_click.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_multi_ranges_backward_drag.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
+["test_selection_cross_shadow_boundary_multi_ranges_backward_click.html"]
+skip-if = ["release_or_beta"] # requires Selection.getComposedRanges to be enabled (Nightly only)
+
 ["test_selection_doubleclick.html"]
 
 ["test_selection_expanding.html"]
diff --git a/layout/generic/test/selection_cross_shadow_boundary_helper.js b/layout/generic/test/selection_cross_shadow_boundary_helper.js
new file mode 100644
index 0000000000..b2a596a27f
--- /dev/null
+++ b/layout/generic/test/selection_cross_shadow_boundary_helper.js
@@ -0,0 +1,28 @@
+// Helper file for test_selection_cross_shadow_boundary_* related tests
+
+function drag(
+  fromTarget,
+  fromX,
+  fromY,
+  toTarget,
+  toX,
+  toY,
+  withAccelKey = false
+) {
+  synthesizeMouse(fromTarget, fromX, fromY, {
+    type: "mousemove",
+    accelKey: withAccelKey,
+  });
+  synthesizeMouse(fromTarget, fromX, fromY, {
+    type: "mousedown",
+    accelKey: withAccelKey,
+  });
+  synthesizeMouse(toTarget, toX, toY, {
+    type: "mousemove",
+    accelKey: withAccelKey,
+  });
+  synthesizeMouse(toTarget, toX, toY, {
+    type: "mouseup",
+    accelKey: withAccelKey,
+  });
+}
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_1_backward_click.html b/layout/generic/test/test_selection_cross_shadow_boundary_1_backward_click.html
new file mode 100644
index 0000000000..ee724b344c
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_1_backward_click.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  document.getElementById("host").attachShadow({ mode: "open" }).innerHTML = "<span>InnerText</span>";
+
+  const inner = host.shadowRoot.firstChild;
+  const rect = inner.getBoundingClientRect();
+
+  // Click the bottom right of "InnerText"
+  synthesizeMouse(inner, rect.width, rect.height, { type: "mousedown"});
+  synthesizeMouse(inner, rect.width, rect.height, { type: "mouseup" });
+
+  // Click the top left of "OuterText"
+  synthesizeMouse(document.getElementById("outer"), 0, 0, { type: "mousedown" , shiftKey: true});
+  synthesizeMouse(document.getElementById("outer"), 0, 0, { type: "mouseup" , shiftKey: true});
+
+  // Above two clicks should select both "OuterText" and "InnerText"
+  const sel = document.getSelection().getComposedRanges(host.shadowRoot)[0];
+
+  // backward selection
+  is(sel.endContainer, inner.firstChild, "endContainer is the InnerText");
+  is(sel.endOffset, 9, "endOffset ends at the last character");
+  is(sel.startContainer, outer.firstChild, "startContainer is the OuterText");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer">OuterText</span>
+  <div id="host"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_1_backward_drag.html b/layout/generic/test/test_selection_cross_shadow_boundary_1_backward_drag.html
new file mode 100644
index 0000000000..f1737eaefa
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_1_backward_drag.html
@@ -0,0 +1,40 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+
+function run() {
+  document.getElementById("host").attachShadow({ mode: "open" }).innerHTML = "<span>InnerText</span>";
+
+  const inner = host.shadowRoot.firstChild;
+  const rect = inner.getBoundingClientRect();
+
+  // Drag from the bottom right of InnerText to the
+  // top left of OuterText.
+  drag(
+    inner,
+    rect.width,
+    rect.height,
+    document.getElementById("outer"),
+    0,
+    0);
+
+  // Above drag selects both "OuterText" and "InnerText"
+  const sel = document.getSelection().getComposedRanges(host.shadowRoot)[0];
+
+  // backward selection
+  is(sel.endContainer, inner.firstChild, "endContainer is the InnerText");
+  is(sel.endOffset, 9, "endOffset ends at the last character");
+  is(sel.startContainer, outer.firstChild, "startContainer is the OuterText");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer">OuterText</span>
+  <div id="host"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_1_forward_click.html b/layout/generic/test/test_selection_cross_shadow_boundary_1_forward_click.html
new file mode 100644
index 0000000000..dcf4f9ad16
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_1_forward_click.html
@@ -0,0 +1,35 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  document.getElementById("host").attachShadow({ mode: "open" }).innerHTML = "<span>InnerText</span>";
+
+  // Click the top left of "OuterText"
+  synthesizeMouse(document.getElementById("outer"), 0, 0, { type: "mousedown" });
+  synthesizeMouse(document.getElementById("outer"), 0, 0, { type: "mouseup" });
+
+  // Click the bottom right of "InnerText"
+  const inner = host.shadowRoot.firstChild;
+  const rect = inner.getBoundingClientRect();
+  synthesizeMouse(inner, rect.width, rect.height, { type: "mousedown", shiftKey: true});
+  synthesizeMouse(inner, rect.width, rect.height, { type: "mouseup" , shiftKey: true});
+
+  // Above two clicks should select both "OuterText" and "InnerText"
+  const sel = document.getSelection().getComposedRanges(host.shadowRoot)[0];
+
+  // forward selection
+  is(sel.startContainer, outer.firstChild, "startContainer is the OuterText");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+  is(sel.endContainer, inner.firstChild, "endContainer is the InnerText");
+  is(sel.endOffset, 9, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer">OuterText</span>
+  <div id="host"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_1_forward_drag.html b/layout/generic/test/test_selection_cross_shadow_boundary_1_forward_drag.html
new file mode 100644
index 0000000000..6a351ff16b
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_1_forward_drag.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  document.getElementById("host").attachShadow({ mode: "open" }).innerHTML = "<span>InnerText</span>";
+
+  const inner = host.shadowRoot.firstChild;
+  const rect = inner.getBoundingClientRect();
+
+  // drag from the top left of OuterText
+  // to the bottom right of InnerText
+  drag(
+    document.getElementById("outer"),
+    0,
+    0,
+    inner,
+    rect.width,
+    rect.height);
+
+  // Above drag selects should select both "OuterText" and "InnerText"
+  const sel = document.getSelection().getComposedRanges(host.shadowRoot)[0];
+
+  // forward selection
+  is(sel.startContainer, outer.firstChild, "startContainer is the OuterText");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+  is(sel.endContainer, inner.firstChild, "endContainer is the InnerText");
+  is(sel.endOffset, 9, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer">OuterText</span>
+  <div id="host"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_2_backward_click.html b/layout/generic/test/test_selection_cross_shadow_boundary_2_backward_click.html
new file mode 100644
index 0000000000..8df867a0a5
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_2_backward_click.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+
+function run() {
+  const root1 = document.getElementById("host1").attachShadow({ mode: "open" });
+  root1.innerHTML = "InnerText1";
+
+  const root2 = document.getElementById("host2").attachShadow({ mode: "open" });
+  root2.innerHTML = "<span>InnerText2</span>";
+
+
+
+  const inner2 = root2.firstChild;
+  const rect = inner2.getBoundingClientRect();
+
+  // Click the bottom right of "InnerText2"
+  synthesizeMouse(inner2, rect.width, rect.height, { type: "mousedown" });
+  synthesizeMouse(inner2, rect.width, rect.height, { type: "mouseup" });
+
+  // Click the top left of "OuterText1"
+  synthesizeMouse(document.getElementById("outer1"), 0, 0, { type: "mousedown", shiftKey: true});
+  synthesizeMouse(document.getElementById("outer1"), 0, 0, { type: "mouseup" , shiftKey: true});
+
+  // Above clicks selects should select
+  // "OuterText1", "OuterText2", "InnerText1" and "InnerText2".
+  const sel = document.getSelection().getComposedRanges(root2)[0];
+
+  // backward selection
+  is(sel.endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(sel.endOffset, 10, "endOffset ends at the last character");
+  is(sel.startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1"></div>
+  <span id="outer2">OuterText2</span>
+  <div id="host2"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_2_backward_drag.html b/layout/generic/test/test_selection_cross_shadow_boundary_2_backward_drag.html
new file mode 100644
index 0000000000..f79512d35e
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_2_backward_drag.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+
+function run() {
+  const root1 = document.getElementById("host1").attachShadow({ mode: "open" });
+  root1.innerHTML = "InnerText1";
+
+  const root2 = document.getElementById("host2").attachShadow({ mode: "open" });
+  root2.innerHTML = "<span>InnerText2</span>";
+
+  const inner2 = root2.firstChild;
+  const rect = inner2.getBoundingClientRect();
+
+  const outer1 = document.getElementById("outer1");
+  // Drag from the bottom right of InnerText2 to
+  // the top left of OuterText1.
+  drag(
+    inner2,
+    rect.width,
+    rect.height,
+    outer1,
+    0,
+    0);
+
+  // Above drag should selects
+  // "OuterText1", "OuterText2", "InnerText1" and "InnerText2".
+  const sel = document.getSelection().getComposedRanges(root2)[0];
+
+  // backward selection
+  is(sel.endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(sel.endOffset, 10, "endOffset ends at the last character");
+  is(sel.startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1"></div>
+  <span id="outer2">OuterText2</span>
+  <div id="host2"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_2_forward_click.html b/layout/generic/test/test_selection_cross_shadow_boundary_2_forward_click.html
new file mode 100644
index 0000000000..2ca2eaeda9
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_2_forward_click.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+
+function run() {
+  const root1 = document.getElementById("host1").attachShadow({ mode: "open" });
+  root1.innerHTML = "InnerText1";
+
+  const root2 = document.getElementById("host2").attachShadow({ mode: "open" });
+  root2.innerHTML = "<span>InnerText2</span>";
+
+  const outer1 = document.getElementById("outer1");
+  // Click the top left of "OuterText1"
+  synthesizeMouse(outer1, 0, 0, { type: "mousedown" });
+  synthesizeMouse(outer1, 0, 0, { type: "mouseup" });
+
+  const inner2 = root2.firstChild;
+  const rect = inner2.getBoundingClientRect();
+
+  // Click the bottom right of "InnerText2"
+  synthesizeMouse(inner2, rect.width, rect.height, { type: "mousedown", shiftKey: true});
+  synthesizeMouse(inner2, rect.width, rect.height, { type: "mouseup" , shiftKey: true});
+
+  // Above clicks should select
+  // "OuterText1", "OuterText2", "InnerText1" and "InnerText2".
+  const sel = document.getSelection().getComposedRanges(root2)[0];
+
+  // forward selection
+  is(sel.startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+  is(sel.endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(sel.endOffset, 10, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1"></div>
+  <span id="outer2">OuterText2</span>
+  <div id="host2"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_2_forward_drag.html b/layout/generic/test/test_selection_cross_shadow_boundary_2_forward_drag.html
new file mode 100644
index 0000000000..b92108de95
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_2_forward_drag.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+
+function run() {
+  const root1 = document.getElementById("host1").attachShadow({ mode: "open" });
+  root1.innerHTML = "InnerText1";
+
+  const root2 = document.getElementById("host2").attachShadow({ mode: "open" });
+  root2.innerHTML = "<span>InnerText2</span>";
+
+  const inner2 = root2.firstChild;
+  const rect = inner2.getBoundingClientRect();
+
+  const outer1 = document.getElementById("outer1");
+  // Drag from the top lef of OuterText1 to the
+  // bottom right of InnerText2.
+  drag(
+    outer1,
+    0,
+    0,
+    inner2,
+    rect.width,
+    rect.height);
+
+  // Above drag should select
+  // "OuterText1", "OuterText2", "InnerText1" and "InnerText2".
+  const sel = document.getSelection().getComposedRanges(root2)[0];
+
+  // forward selection
+  is(sel.startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(sel.startOffset, 0, "startOffset starts at the first character");
+  is(sel.endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(sel.endOffset, 10, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1"></div>
+  <span id="outer2">OuterText2</span>
+  <div id="host2"></div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_backward_click.html b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_backward_click.html
new file mode 100644
index 0000000000..a2a0d0e2be
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_backward_click.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  const inner1 = host1.shadowRoot.querySelector("span");
+  const rect1 = inner1.getBoundingClientRect();
+
+  // Click the bottom right of "InnerText1"
+  synthesizeMouse(inner1, rect1.width - 1, rect1.height - 1, { type: "mousedown" });
+  synthesizeMouse(inner1, rect1.width - 1, rect1.height - 1, { type: "mouseup" });
+
+  // Click the top left of "OuterText1"
+  synthesizeMouse(document.getElementById("outer1"), 0, 0, { type: "mousedown", shiftKey: true });
+  synthesizeMouse(document.getElementById("outer1"), 0, 0, { type: "mouseup", shiftKey: true });
+
+  const inner2 = host2.shadowRoot.querySelector("span");
+  const rect2 = inner2.getBoundingClientRect();
+
+  // Click the bottom right of "InnerText2" with accelKey
+  synthesizeMouse(inner2, rect2.width, rect2.height, { type: "mousedown", accelKey: true});
+  synthesizeMouse(inner2, rect2.width, rect2.height, { type: "mouseup" , accelKey: true});
+
+  // Click the top left of "OuterText2"
+  synthesizeMouse(document.getElementById("outer2"), 1, 1, { type: "mousedown", shiftKey: true});
+  synthesizeMouse(document.getElementById("outer2"), 1, 1, { type: "mouseup", shiftKey: true});
+
+  const ranges = document.getSelection().getComposedRanges(host1.shadowRoot, host2.shadowRoot);
+  is(ranges.length, 2, "Above two drag selection should produce two ranges");
+
+  is(ranges[0].startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(ranges[0].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[0].endContainer, inner1.firstChild, "endContainer is the InnerText1");
+  is(ranges[0].endOffset, 10, "endOffset ends at the last character");
+
+  is(ranges[1].startContainer, outer2.firstChild, "startContainer is the OuterText2");
+  is(ranges[1].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[1].endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(ranges[1].endOffset, 10, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1">
+    <template shadowrootmode="open">
+      <span>InnerText1</span>
+    </template>
+  </div>
+  <br>
+  <span id="outer2">OuterText2</span>
+  <div id="host2">
+    <template shadowrootmode="open">
+      <span>InnerText2</span>
+    </template>
+  </div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_backward_drag.html b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_backward_drag.html
new file mode 100644
index 0000000000..317ee4f973
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_backward_drag.html
@@ -0,0 +1,65 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  const inner1 = host1.shadowRoot.querySelector("span");
+  const rect1 = inner1.getBoundingClientRect();
+
+  // drag from the bottom right of InnerText1
+  // to the top left of OuterText1
+  drag(
+    inner1,
+    rect1.width - 1,
+    rect1.height - 1,
+    document.getElementById("outer1"),
+    1,
+    1);
+
+  const inner2 = host2.shadowRoot.querySelector("span");
+  const rect2 = inner2.getBoundingClientRect();
+  // drag from the bottom right of InnerText2
+  // to the top left of OuterText2
+  drag(
+    inner2,
+    rect2.width,
+    rect2.height,
+    document.getElementById("outer2"),
+    1,
+    1,
+    true /* accelKey */);
+
+  const ranges = document.getSelection().getComposedRanges(host1.shadowRoot, host2.shadowRoot);
+  is(ranges.length, 2, "Above two drag selection should produce two ranges");
+
+  is(ranges[0].startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(ranges[0].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[0].endContainer, inner1.firstChild, "endContainer is the InnerText1");
+  is(ranges[0].endOffset, 10, "endOffset ends at the last character");
+
+  is(ranges[1].startContainer, outer2.firstChild, "startContainer is the OuterText2");
+  is(ranges[1].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[1].endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(ranges[1].endOffset, 10, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1">
+    <template shadowrootmode="open">
+      <span>InnerText1</span>
+    </template>
+  </div>
+  <br>
+  <span id="outer2">OuterText2</span>
+  <div id="host2">
+    <template shadowrootmode="open">
+      <span>InnerText2</span>
+    </template>
+  </div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_forward_click.html b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_forward_click.html
new file mode 100644
index 0000000000..931c01fca0
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_forward_click.html
@@ -0,0 +1,59 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  // Click the top left of "OuterText1"
+  synthesizeMouse(document.getElementById("outer1"), 1, 1, { type: "mousedown" });
+  synthesizeMouse(document.getElementById("outer1"), 1, 1, { type: "mouseup" });
+
+  const inner1 = host1.shadowRoot.querySelector("span");
+  const rect1 = inner1.getBoundingClientRect();
+  // Click the bottom right of "InnerText1"
+  synthesizeMouse(inner1, rect1.width - 1, rect1.height - 1, { type: "mousedown", shiftKey: true});
+  synthesizeMouse(inner1, rect1.width - 1, rect1.height - 1, { type: "mouseup" , shiftKey: true});
+
+  // Click the top left of "OuterText2" with accelKey
+  synthesizeMouse(document.getElementById("outer2"), 1, 1, { type: "mousedown", accelKey: true});
+  synthesizeMouse(document.getElementById("outer2"), 1, 1, { type: "mouseup", accelKey: true});
+
+  const inner2 = host2.shadowRoot.querySelector("span");
+  const rect2 = inner2.getBoundingClientRect();
+  // Click the bottom right of "InnerText2"
+  synthesizeMouse(inner2, rect2.width, rect2.height, { type: "mousedown", shiftKey: true});
+  synthesizeMouse(inner2, rect2.width, rect2.height, { type: "mouseup" , shiftKey: true});
+
+  const ranges = document.getSelection().getComposedRanges(host1.shadowRoot, host2.shadowRoot);
+  is(ranges.length, 2, "Above two drag selection should produce two ranges");
+
+  is(ranges[0].startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(ranges[0].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[0].endContainer, inner1.firstChild, "endContainer is the InnerText1");
+  is(ranges[0].endOffset, 10, "endOffset ends at the last character");
+
+  is(ranges[1].startContainer, outer2.firstChild, "startContainer is the OuterText2");
+  is(ranges[1].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[1].endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(ranges[1].endOffset, 10, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1">
+    <template shadowrootmode="open">
+      <span>InnerText1</span>
+    </template>
+  </div>
+  <br>
+  <span id="outer2">OuterText2</span>
+  <div id="host2">
+    <template shadowrootmode="open">
+      <span>InnerText2</span>
+    </template>
+  </div>
+</body>
diff --git a/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_forward_drag.html b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_forward_drag.html
new file mode 100644
index 0000000000..b45e588685
--- /dev/null
+++ b/layout/generic/test/test_selection_cross_shadow_boundary_multi_ranges_forward_drag.html
@@ -0,0 +1,65 @@
+<!DOCTYPE HTML>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script type="application/javascript" src="/tests/layout/generic/test/selection_cross_shadow_boundary_helper.js"></script>
+<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+<script>
+SimpleTest.waitForExplicitFinish();
+function run() {
+  const inner1 = host1.shadowRoot.querySelector("span");
+  const rect1 = inner1.getBoundingClientRect();
+
+  // drag from the top left of OuterText1
+  // to the bottom right of InnerText1
+  drag(
+    document.getElementById("outer1"),
+    1,
+    1,
+    inner1,
+    rect1.width - 1,
+    rect1.height - 1);
+
+  const inner2 = host2.shadowRoot.querySelector("span");
+  const rect2 = inner2.getBoundingClientRect();
+  // drag from the top left of OuterText2
+  // to the bottom right of InnerText2
+  drag(
+    document.getElementById("outer2"),
+    1,
+    1,
+    inner2,
+    rect2.width,
+    rect2.height,
+    true /* accelKey */);
+
+  const ranges = document.getSelection().getComposedRanges(host1.shadowRoot, host2.shadowRoot);
+  is(ranges.length, 2, "Above two drag selection should produce two ranges");
+
+  is(ranges[0].startContainer, outer1.firstChild, "startContainer is the OuterText1");
+  is(ranges[0].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[0].endContainer, inner1.firstChild, "endContainer is the InnerText1");
+  is(ranges[0].endOffset, 10, "endOffset ends at the last character");
+
+  is(ranges[1].startContainer, outer2.firstChild, "startContainer is the OuterText2");
+  is(ranges[1].startOffset, 0, "startOffset starts at the first character");
+  is(ranges[1].endContainer, inner2.firstChild, "endContainer is the InnerText2");
+  is(ranges[1].endOffset, 10, "endOffset ends at the last character");
+
+  SimpleTest.finish();
+}
+</script>
+<body onload="SimpleTest.waitForFocus(run);">
+  <span id="outer1">OuterText1</span>
+  <div id="host1">
+    <template shadowrootmode="open">
+      <span>InnerText1</span>
+    </template>
+  </div>
+  <br>
+  <span id="outer2">OuterText2</span>
+  <div id="host2">
+    <template shadowrootmode="open">
+      <span>InnerText2</span>
+    </template>
+  </div>
+</body>
diff --git a/layout/inspector/InspectorUtils.cpp b/layout/inspector/InspectorUtils.cpp
index f1886a0dd0..d174c16424 100644
--- a/layout/inspector/InspectorUtils.cpp
+++ b/layout/inspector/InspectorUtils.cpp
@@ -415,6 +415,7 @@ static uint32_t CollectAtRules(ServoCSSRuleList& aRuleList,
       case StyleCssRuleType::Media:
       case StyleCssRuleType::Supports:
       case StyleCssRuleType::LayerBlock:
+      case StyleCssRuleType::Property:
       case StyleCssRuleType::Container: {
         Unused << aResult.AppendElement(OwningNonNull(*rule), fallible);
         break;
@@ -425,7 +426,6 @@ static uint32_t CollectAtRules(ServoCSSRuleList& aRuleList,
       case StyleCssRuleType::LayerStatement:
       case StyleCssRuleType::FontFace:
       case StyleCssRuleType::Page:
-      case StyleCssRuleType::Property:
       case StyleCssRuleType::Keyframes:
       case StyleCssRuleType::Keyframe:
       case StyleCssRuleType::Margin:
@@ -433,6 +433,8 @@ static uint32_t CollectAtRules(ServoCSSRuleList& aRuleList,
       case StyleCssRuleType::CounterStyle:
       case StyleCssRuleType::FontFeatureValues:
       case StyleCssRuleType::FontPaletteValues:
+      case StyleCssRuleType::Scope:
+      case StyleCssRuleType::StartingStyle:
         break;
     }
 
@@ -1000,22 +1002,19 @@ void InspectorUtils::GetCSSRegisteredProperties(
 }
 
 /* static */
-void InspectorUtils::GetRuleBodyTextOffsets(
-    GlobalObject&, const nsACString& aInitialText,
-    Nullable<InspectorGetRuleBodyTextResult>& aResult) {
-  uint32_t resultStartOffset;
-  uint32_t resultEndOffset;
-
-  if (!Servo_GetRuleBodyTextOffsets(&aInitialText, &resultStartOffset,
-                                    &resultEndOffset)) {
-    aResult.SetNull();
-    return;
-  }
-
-  InspectorGetRuleBodyTextResult& offsets = aResult.SetValue();
-  offsets.mStartOffset = resultStartOffset;
-  offsets.mEndOffset = resultEndOffset;
+void InspectorUtils::GetRuleBodyText(GlobalObject&,
+                                     const nsACString& aInitialText,
+                                     nsACString& aBodyText) {
+  Servo_GetRuleBodyText(&aInitialText, &aBodyText);
 }
 
+/* static */
+void InspectorUtils::ReplaceBlockRuleBodyTextInStylesheet(
+    GlobalObject&, const nsACString& aStyleSheetText, uint32_t aLine,
+    uint32_t aColumn, const nsACString& aNewBodyText,
+    nsACString& aNewStyleSheetText) {
+  Servo_ReplaceBlockRuleBodyTextInStylesheetText(
+      &aStyleSheetText, aLine, aColumn, &aNewBodyText, &aNewStyleSheetText);
+}
 }  // namespace dom
 }  // namespace mozilla
diff --git a/layout/inspector/InspectorUtils.h b/layout/inspector/InspectorUtils.h
index f375e51472..9d64823fc4 100644
--- a/layout/inspector/InspectorUtils.h
+++ b/layout/inspector/InspectorUtils.h
@@ -270,11 +270,18 @@ class InspectorUtils {
       nsTArray<InspectorCSSPropertyDefinition>& aResult);
 
   /**
-   * Get the rule body text start and end offsets within aInitialText
+   * Get the rule body text within aInitialText
    */
-  static void GetRuleBodyTextOffsets(
-      GlobalObject&, const nsACString& aInitialText,
-      Nullable<InspectorGetRuleBodyTextResult>& aResult);
+  static void GetRuleBodyText(GlobalObject&, const nsACString& aInitialText,
+                              nsACString& aBodyText);
+
+  /**
+   * Replace the rule body text in aStyleSheetText at passed line and column
+   */
+  static void ReplaceBlockRuleBodyTextInStylesheet(
+      GlobalObject&, const nsACString& aStyleSheetText, uint32_t aLine,
+      uint32_t aColumn, const nsACString& aNewBodyText,
+      nsACString& aNewStyleSheetText);
 };
 
 }  // namespace mozilla::dom
diff --git a/layout/inspector/ServoStyleRuleMap.cpp b/layout/inspector/ServoStyleRuleMap.cpp
index b67d0c98fc..188c4f5329 100644
--- a/layout/inspector/ServoStyleRuleMap.cpp
+++ b/layout/inspector/ServoStyleRuleMap.cpp
@@ -86,7 +86,9 @@ void ServoStyleRuleMap::RuleRemoved(StyleSheet& aStyleSheet,
     case StyleCssRuleType::Supports:
     case StyleCssRuleType::LayerBlock:
     case StyleCssRuleType::Container:
-    case StyleCssRuleType::Document: {
+    case StyleCssRuleType::Document:
+    case StyleCssRuleType::Scope:
+    case StyleCssRuleType::StartingStyle: {
       // See the comment in SheetRemoved.
       mTable.Clear();
       break;
@@ -124,7 +126,9 @@ void ServoStyleRuleMap::FillTableFromRule(css::Rule& aRule) {
     case StyleCssRuleType::Media:
     case StyleCssRuleType::Supports:
     case StyleCssRuleType::Container:
-    case StyleCssRuleType::Document: {
+    case StyleCssRuleType::Document:
+    case StyleCssRuleType::Scope:
+    case StyleCssRuleType::StartingStyle: {
       auto& rule = static_cast<css::GroupRule&>(aRule);
       FillTableFromRuleList(*rule.CssRules());
       break;
diff --git a/layout/inspector/tests/mochitest.toml b/layout/inspector/tests/mochitest.toml
index e51941752b..b45742b727 100644
--- a/layout/inspector/tests/mochitest.toml
+++ b/layout/inspector/tests/mochitest.toml
@@ -1,6 +1,7 @@
 [DEFAULT]
 prefs = [
   "layout.css.basic-shape-rect.enabled=true",
+  "layout.css.basic-shape-shape.enabled=true",
   "layout.css.basic-shape-xywh.enabled=true",
   "layout.css.properties-and-values.enabled=true",
   "layout.css.transition-behavior.enabled=true",
@@ -78,6 +79,8 @@ skip-if = ["os == 'android'"]
 
 ["test_parseStyleSheet_nested.html"]
 
+["test_replaceBlockRuleBodyTextInStylesheet.html"]
+
 ["test_rgba_to_color_name.html"]
 
 ["test_selectormatcheselement.html"]
diff --git a/layout/inspector/tests/test_bug877690.html b/layout/inspector/tests/test_bug877690.html
index 9e5efca0d3..668d18200e 100644
--- a/layout/inspector/tests/test_bug877690.html
+++ b/layout/inspector/tests/test_bug877690.html
@@ -217,10 +217,13 @@ function do_test() {
   ok(testValues(values, expected), "property box-shadow's values");
 
   // Regression test for bug 1255379.
+  var shapeFunction = [ "close", "evenodd", "nonzero", "by", "to", "cw", "ccw",
+                        "small", "large" ];
   var expected = [ "inherit", "initial", "unset", "revert", "revert-layer",
                    "none", "url", "polygon", "circle", "ellipse", "inset",
-                   "path", "rect", "xywh", "fill-box", "stroke-box", "view-box",
-                   "margin-box", "border-box", "padding-box", "content-box" ];
+                   "path", "rect", "xywh", "fill-box", "stroke-box",
+                   "view-box", "margin-box", "border-box", "padding-box",
+                   "content-box", ...shapeFunction ];
   var values = InspectorUtils.getCSSValuesForProperty("clip-path");
   ok(testValues(values, expected), "property clip-path's values");
 
diff --git a/layout/inspector/tests/test_getCSSPseudoElementNames.html b/layout/inspector/tests/test_getCSSPseudoElementNames.html
index 255f58b889..356d4a89bc 100644
--- a/layout/inspector/tests/test_getCSSPseudoElementNames.html
+++ b/layout/inspector/tests/test_getCSSPseudoElementNames.html
@@ -22,6 +22,7 @@
       "::highlight",
       "::placeholder",
       "::selection",
+      "::target-text",
       "::-moz-color-swatch",
       "::-moz-focus-inner",
       "::-moz-meter-bar",
diff --git a/layout/inspector/tests/test_replaceBlockRuleBodyTextInStylesheet.html b/layout/inspector/tests/test_replaceBlockRuleBodyTextInStylesheet.html
new file mode 100644
index 0000000000..e6385978ba
--- /dev/null
+++ b/layout/inspector/tests/test_replaceBlockRuleBodyTextInStylesheet.html
@@ -0,0 +1,209 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test InspectorUtils::replaceBlockRuleBodyTextInStylesheet</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+  <style>
+#test-simple {
+  color: #f0c;
+}
+#test-unicode,[data-unicode="🦄👨‍👩‍👧‍👦"]::after {
+  content: /* test comment */ "👨‍👩‍👧‍👦🦄";
+  outline: 2px solid salmon;
+}
+#test-empty {} /* 🛠️⚒️🛠️ */ #test-same-line { font-size: 3em; }
+#test-nested-parent {
+  color: tomato;
+  #test-nested-child {
+    background: gold;
+  }
+}#test-after-closing-bracket{--modified:false}
+  </style>
+  <script>SimpleTest.waitForExplicitFinish();</script>
+  <script defer>
+    const InspectorUtils = SpecialPowers.InspectorUtils;
+    let stylesheet = document.styleSheets[1];
+    let authoredStyleSheetText = document.querySelector("style").textContent;
+
+    const existingRulesAuthoredText = [
+`#test-simple {
+  color: #f0c;
+}`,
+`#test-unicode,[data-unicode="🦄👨‍👩‍👧‍👦"]::after {
+  content: /* test comment */ "👨‍👩‍👧‍👦🦄";
+  outline: 2px solid salmon;
+}`,
+`#test-empty {}`,
+`#test-same-line { font-size: 3em; }`,
+`#test-nested-parent {
+  color: tomato;
+  #test-nested-child {
+    background: gold;
+  }
+}`,
+`#test-nested-child {
+    background: gold;
+  }`,
+`#test-after-closing-bracket{--modified:false}`,
+];
+
+    const replaceBlockRuleBodyTextInStylesheet = (rule, newBodyText) => {
+      return InspectorUtils.replaceBlockRuleBodyTextInStylesheet(
+        authoredStyleSheetText,
+        InspectorUtils.getRelativeRuleLine(rule),
+        InspectorUtils.getRuleColumn(rule),
+        newBodyText
+      )};
+
+    info("Check a simple case");
+    let newBodyText = `border-color: cyan;`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[0], newBodyText),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[0],
+        `#test-simple {${newBodyText}}`,
+      ),
+      "Got the expected result for #test-simple"
+    );
+
+    info("Check that the rule body can be emptied");
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[0], ""),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[0],
+        `#test-simple {}`,
+      ),
+      "Successfuly removed rule content for #test-simple"
+    );
+
+    info("Check that it can handle unicode characters");
+    newBodyText = `content: "o 🦊 o";`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[1], newBodyText),
+      authoredStyleSheetText.replace(existingRulesAuthoredText[1],
+        `#test-unicode,[data-unicode="🦄👨‍👩‍👧‍👦"]::after {${newBodyText}}`,
+      ),
+      "Got the expected result for #test-unicode"
+    );
+
+    info("Check that it can replace content of an empty rule");
+    newBodyText = `font-family: "Zilla;"`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[2], newBodyText),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[2],
+        `#test-empty {${newBodyText}}`,
+      ),
+      "Got the expected result for #test-empty"
+    );
+
+    info("Check that it can handle a rule on a same line as another rule");
+    newBodyText = `color: pink;`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[3], newBodyText),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[3],
+        `#test-same-line {${newBodyText}}`,
+      ),
+      "Got the expected result for #test-same-line"
+    );
+
+    info("Check that it can handle a rule with a child rule");
+    newBodyText = `background: silver;
+    & > span {
+      color: white;
+    }`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[4], newBodyText),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[4],
+        `#test-nested-parent {${newBodyText}}`,
+      ),
+      "Got the expected result for #test-nested-parent"
+    );
+
+    info("Check that it can handle a nested rule");
+    newBodyText = `color: white;height: 100%;`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[4].cssRules[0], newBodyText),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[5],
+        `#test-nested-child {${newBodyText}}`,
+      ),
+      "Got the expected result for #test-nested-child"
+    );
+
+    // Covering fix for Bug 1890775
+    info("Check that it can handle rules  whose declaration is directly after the } of the previous rule, without spaces");
+    isnot(
+      InspectorUtils.getRelativeRuleLine(stylesheet.cssRules[5]),
+      1,
+      "The rule should not be on the first line of the stylesheet to check the issue it covers"
+    );
+    newBodyText = `--modified:true`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[5], newBodyText),
+      authoredStyleSheetText.replace(
+        existingRulesAuthoredText[6],
+        `#test-after-closing-bracket{${newBodyText}}`,
+      ),
+      "Got the expected result for #test-after-closing-bracket"
+    );
+
+    info("Checking fix for files with crlf EOL sequence");
+    let styleEl = document.createElement("style");
+    let ruleText = `#test-after-closing-bracket-crlf{--modified-crlf:false}`
+    authoredStyleSheetText = `\r\nhtml{}${ruleText}`;
+    styleEl.append(document.createTextNode(authoredStyleSheetText));
+    document.head.append(styleEl);
+    stylesheet = document.styleSheets[2];
+    isnot(
+      InspectorUtils.getRelativeRuleLine(stylesheet.cssRules[1]),
+      1,
+      "The rule should not be on the first line of the stylesheet to check the issue it covers"
+    );
+    newBodyText = `--modified-crlf:true`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[1], newBodyText),
+      authoredStyleSheetText.replace(
+        ruleText,
+        `#test-after-closing-bracket-crlf{${newBodyText}}`,
+      ),
+      "Got the expected result for #test-after-closing-bracket-crlf"
+    );
+
+    info("Checking fix for files with cr EOL sequence");
+    ruleText = `#test-after-closing-bracket-cr{--modified-cr:false}`
+    authoredStyleSheetText = `\rhtml{}${ruleText}`;
+    styleEl.innerText = "";
+    styleEl.append(document.createTextNode(authoredStyleSheetText));
+    isnot(
+      InspectorUtils.getRelativeRuleLine(stylesheet.cssRules[1]),
+      1,
+      "The rule should not be on the first line of the stylesheet to check the issue it covers"
+    );
+    newBodyText = `--modified-cr:true`;
+    is(
+      replaceBlockRuleBodyTextInStylesheet(stylesheet.cssRules[1], newBodyText),
+      authoredStyleSheetText.replace(
+        ruleText,
+        `#test-after-closing-bracket-cr{${newBodyText}}`,
+      ),
+      "Got the expected result for #test-after-closing-bracket-cr"
+    );
+
+    SimpleTest.finish();
+  </script>
+</head>
+<body>
+<h1>Test InspectorUtils::replaceBlockRuleBodyTextInStylesheet</h1>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/layout/mathml/nsMathMLContainerFrame.cpp b/layout/mathml/nsMathMLContainerFrame.cpp
index b63792c288..fc334d1cae 100644
--- a/layout/mathml/nsMathMLContainerFrame.cpp
+++ b/layout/mathml/nsMathMLContainerFrame.cpp
@@ -829,39 +829,33 @@ static nscoord AddInterFrameSpacingToSize(ReflowOutput& aDesiredSize,
 
 /* virtual */
 void nsMathMLContainerFrame::MarkIntrinsicISizesDirty() {
-  mIntrinsicWidth = NS_INTRINSIC_ISIZE_UNKNOWN;
+  mIntrinsicISize = NS_INTRINSIC_ISIZE_UNKNOWN;
   nsContainerFrame::MarkIntrinsicISizesDirty();
 }
 
-void nsMathMLContainerFrame::UpdateIntrinsicWidth(
+void nsMathMLContainerFrame::UpdateIntrinsicISize(
     gfxContext* aRenderingContext) {
-  if (mIntrinsicWidth == NS_INTRINSIC_ISIZE_UNKNOWN) {
+  if (mIntrinsicISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
     ReflowOutput desiredSize(GetWritingMode());
     GetIntrinsicISizeMetrics(aRenderingContext, desiredSize);
 
     // Include the additional width added by FixInterFrameSpacing to ensure
     // consistent width calculations.
     AddInterFrameSpacingToSize(desiredSize, this);
-    mIntrinsicWidth = desiredSize.ISize(GetWritingMode());
+    mIntrinsicISize = desiredSize.ISize(GetWritingMode());
   }
 }
 
 /* virtual */
 nscoord nsMathMLContainerFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-  UpdateIntrinsicWidth(aRenderingContext);
-  result = mIntrinsicWidth;
-  return result;
+  UpdateIntrinsicISize(aRenderingContext);
+  return mIntrinsicISize;
 }
 
 /* virtual */
 nscoord nsMathMLContainerFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-  UpdateIntrinsicWidth(aRenderingContext);
-  result = mIntrinsicWidth;
-  return result;
+  UpdateIntrinsicISize(aRenderingContext);
+  return mIntrinsicISize;
 }
 
 /* virtual */
diff --git a/layout/mathml/nsMathMLContainerFrame.h b/layout/mathml/nsMathMLContainerFrame.h
index 805d7e03ca..24bc86c338 100644
--- a/layout/mathml/nsMathMLContainerFrame.h
+++ b/layout/mathml/nsMathMLContainerFrame.h
@@ -37,9 +37,7 @@ class nsMathMLContainerFrame : public nsContainerFrame, public nsMathMLFrame {
  public:
   nsMathMLContainerFrame(ComputedStyle* aStyle, nsPresContext* aPresContext,
                          ClassID aID)
-      : nsContainerFrame(aStyle, aPresContext, aID),
-        mIntrinsicWidth(NS_INTRINSIC_ISIZE_UNKNOWN),
-        mBlockStartAscent(0) {}
+      : nsContainerFrame(aStyle, aPresContext, aID) {}
 
   NS_DECL_QUERYFRAME_TARGET(nsMathMLContainerFrame)
   NS_DECL_QUERYFRAME
@@ -341,13 +339,13 @@ class nsMathMLContainerFrame : public nsContainerFrame, public nsMathMLFrame {
   static void DidReflowChildren(nsIFrame* aFirst, nsIFrame* aStop = nullptr);
 
   /**
-   * Recompute mIntrinsicWidth if it's not already up to date.
+   * Recompute mIntrinsicISize if it's not already up to date.
    */
-  void UpdateIntrinsicWidth(gfxContext* aRenderingContext);
+  void UpdateIntrinsicISize(gfxContext* aRenderingContext);
 
-  nscoord mIntrinsicWidth;
+  nscoord mIntrinsicISize = NS_INTRINSIC_ISIZE_UNKNOWN;
 
-  nscoord mBlockStartAscent;
+  nscoord mBlockStartAscent = 0;
 
  private:
   class RowChildFrameIterator;
@@ -429,8 +427,7 @@ class nsMathMLmathBlockFrame final : public nsBlockFrame {
  protected:
   explicit nsMathMLmathBlockFrame(ComputedStyle* aStyle,
                                   nsPresContext* aPresContext)
-      : nsBlockFrame(aStyle, aPresContext, kClassID) {
-  }
+      : nsBlockFrame(aStyle, aPresContext, kClassID) {}
   virtual ~nsMathMLmathBlockFrame() = default;
 };
 
diff --git a/layout/mathml/nsMathMLmoFrame.cpp b/layout/mathml/nsMathMLmoFrame.cpp
index e0d68234ae..e27709c0b0 100644
--- a/layout/mathml/nsMathMLmoFrame.cpp
+++ b/layout/mathml/nsMathMLmoFrame.cpp
@@ -8,6 +8,7 @@
 
 #include "gfxContext.h"
 #include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_mathml.h"
 #include "nsCSSValue.h"
 #include "nsLayoutUtils.h"
 #include "nsPresContext.h"
@@ -145,15 +146,17 @@ void nsMathMLmoFrame::ProcessTextData() {
   mFlags |= allFlags & NS_MATHML_OPERATOR_ACCENT;
   mFlags |= allFlags & NS_MATHML_OPERATOR_MOVABLELIMITS;
 
-  // see if this is an operator that should be centered to cater for
-  // fonts that are not math-aware
-  if (1 == length) {
-    if ((ch == '+') || (ch == '=') || (ch == '*') ||
-        (ch == 0x2212) ||  // &minus;
-        (ch == 0x2264) ||  // &le;
-        (ch == 0x2265) ||  // &ge;
-        (ch == 0x00D7)) {  // &times;
-      mFlags |= NS_MATHML_OPERATOR_CENTERED;
+  if (!StaticPrefs::mathml_centered_operators_disabled()) {
+    // see if this is an operator that should be centered to cater for
+    // fonts that are not math-aware
+    if (1 == length) {
+      if ((ch == '+') || (ch == '=') || (ch == '*') ||
+          (ch == 0x2212) ||  // &minus;
+          (ch == 0x2264) ||  // &le;
+          (ch == 0x2265) ||  // &ge;
+          (ch == 0x00D7)) {  // &times;
+        mFlags |= NS_MATHML_OPERATOR_CENTERED;
+      }
     }
   }
 
@@ -593,9 +596,15 @@ nsMathMLmoFrame::Stretch(DrawTarget* aDrawTarget,
 
   // get the leading to be left at the top and the bottom of the stretched char
   // this seems more reliable than using fm->GetLeading() on suspicious fonts
-  nscoord em;
-  GetEmHeight(fm, em);
-  nscoord leading = NSToCoordRound(0.2f * em);
+  const nscoord leading = [&fm] {
+    if (StaticPrefs::
+            mathml_top_bottom_spacing_for_stretchy_operators_disabled()) {
+      return 0;
+    }
+    nscoord em;
+    GetEmHeight(fm, em);
+    return NSToCoordRound(0.2f * (float)em);
+  }();
 
   // Operators that are stretchy, or those that are to be centered
   // to cater for fonts that are not math-aware, are handled by the MathMLChar
diff --git a/layout/mathml/nsMathMLmtableFrame.h b/layout/mathml/nsMathMLmtableFrame.h
index 1a801de8fc..dee6c5ba7a 100644
--- a/layout/mathml/nsMathMLmtableFrame.h
+++ b/layout/mathml/nsMathMLmtableFrame.h
@@ -222,7 +222,8 @@ class nsMathMLmtdFrame final : public nsTableCellFrame {
                       mozilla::nsDisplayListBuilder* aBuilder,
                       const mozilla::nsDisplayListSet& aLists) override;
 
-  LogicalMargin GetBorderWidth(WritingMode aWM) const override;
+  mozilla::LogicalMargin GetBorderWidth(
+      mozilla::WritingMode aWM) const override;
 
   nsMargin GetBorderOverflow() override;
 
diff --git a/layout/painting/RetainedDisplayListBuilder.cpp b/layout/painting/RetainedDisplayListBuilder.cpp
index ca8f37a252..18e9612ff2 100644
--- a/layout/painting/RetainedDisplayListBuilder.cpp
+++ b/layout/painting/RetainedDisplayListBuilder.cpp
@@ -1313,23 +1313,6 @@ bool RetainedDisplayListBuilder::ShouldBuildPartial(
   return true;
 }
 
-void RetainedDisplayListBuilder::InvalidateCaretFramesIfNeeded() {
-  if (mPreviousCaret == mBuilder.GetCaretFrame()) {
-    // The current caret frame is the same as the previous one.
-    return;
-  }
-
-  if (mPreviousCaret) {
-    mPreviousCaret->MarkNeedsDisplayItemRebuild();
-  }
-
-  if (mBuilder.GetCaretFrame()) {
-    mBuilder.GetCaretFrame()->MarkNeedsDisplayItemRebuild();
-  }
-
-  mPreviousCaret = mBuilder.GetCaretFrame();
-}
-
 class AutoClearFramePropsArray {
  public:
   explicit AutoClearFramePropsArray(size_t aCapacity) : mFrames(aCapacity) {}
@@ -1585,7 +1568,7 @@ PartialUpdateResult RetainedDisplayListBuilder::AttemptPartialUpdate(
     MarkFramesWithItemsAndImagesModified(&mList);
   }
 
-  InvalidateCaretFramesIfNeeded();
+  mBuilder.InvalidateCaretFramesIfNeeded();
 
   // We set the override dirty regions during ComputeRebuildRegion or in
   // DisplayPortUtils::InvalidateForDisplayPortChange. The display port change
diff --git a/layout/painting/RetainedDisplayListBuilder.h b/layout/painting/RetainedDisplayListBuilder.h
index e9f5b56d1b..e255c4d3aa 100644
--- a/layout/painting/RetainedDisplayListBuilder.h
+++ b/layout/painting/RetainedDisplayListBuilder.h
@@ -200,11 +200,6 @@ class RetainedDisplayListBuilder {
   void IncrementSubDocPresShellPaintCount(nsDisplayItem* aItem);
 
   /**
-   * Invalidates the current and previous caret frame if they have changed.
-   */
-  void InvalidateCaretFramesIfNeeded();
-
-  /**
    * A simple early exit heuristic to avoid slow partial display list rebuilds.
    * Returns true if a partial display list build should be attempted.
    */
@@ -272,7 +267,6 @@ class RetainedDisplayListBuilder {
 
   nsDisplayListBuilder mBuilder;
   RetainedDisplayList mList;
-  WeakFrame mPreviousCaret;
   RetainedDisplayListMetrics mMetrics;
   RetainedDisplayListData mData;
 };
diff --git a/layout/painting/crashtests/crashtests.list b/layout/painting/crashtests/crashtests.list
index af2df7830c..954e2de6e2 100644
--- a/layout/painting/crashtests/crashtests.list
+++ b/layout/painting/crashtests/crashtests.list
@@ -18,7 +18,7 @@ load 1469472.html
 load 1477831-1.html
 load 1504033.html
 load 1514544-1.html
-asserts(0-1) asserts-if(Android,0-2) load 1547420-1.html
+asserts(0-5) load 1547420-1.html
 load 1549909.html
 load 1551389-1.html
 asserts(0-2) load 1555819-1.html
diff --git a/layout/painting/nsCSSRenderingGradients.cpp b/layout/painting/nsCSSRenderingGradients.cpp
index 2fb2f0b024..db30d4fefc 100644
--- a/layout/painting/nsCSSRenderingGradients.cpp
+++ b/layout/painting/nsCSSRenderingGradients.cpp
@@ -1195,15 +1195,16 @@ class MOZ_STACK_CLASS WrColorStopInterpolator
   WrColorStopInterpolator(
       const nsTArray<ColorStop>& aStops,
       const StyleColorInterpolationMethod& aStyleColorInterpolationMethod,
-      float aOpacity, nsTArray<wr::GradientStop>& aResult)
-      : ColorStopInterpolator(aStops, aStyleColorInterpolationMethod),
+      float aOpacity, nsTArray<wr::GradientStop>& aResult, bool aExtendLastStop)
+      : ColorStopInterpolator(aStops, aStyleColorInterpolationMethod,
+                              aExtendLastStop),
         mResult(aResult),
         mOpacity(aOpacity),
         mOutputStop(0) {}
 
   void CreateStops() {
     mResult.SetLengthAndRetainStorage(0);
-    // we always emit at least two stops (start and end) for each input stop,
+    // We always emit at least two stops (start and end) for each input stop,
     // which avoids ambiguity with incomplete oklch/lch/hsv/hsb color stops for
     // the last stop pair, where the last color stop can't be interpreted on its
     // own because it actually depends on the previous stop.
@@ -1257,11 +1258,26 @@ void nsCSSGradientRenderer::BuildWebRenderParameters(
   // * https://bugzilla.mozilla.org/show_bug.cgi?id=1248178
   StyleColorInterpolationMethod styleColorInterpolationMethod =
       mGradient->ColorInterpolationMethod();
-  if (mStops.Length() >= 2 &&
-      (styleColorInterpolationMethod.space != StyleColorSpace::Srgb ||
-       gfxPlatform::GetCMSMode() == CMSMode::All)) {
+  // For colorspaces supported by WebRender (Srgb, Hsl, Hwb) we technically do
+  // not need to add extra stops, but the only one of those colorspaces that
+  // appears frequently is Srgb, and Srgb still needs extra stops if CMS is
+  // enabled.  Hsl/Hwb need extra stops if StyleHueInterpolationMethod is not
+  // Shorter, or if CMS is enabled.
+  //
+  // It's probably best to keep this logic as simple as possible, see
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=1885716 for an example of
+  // what can happen if we try to be clever here.
+  if (styleColorInterpolationMethod.space != StyleColorSpace::Srgb ||
+      gfxPlatform::GetCMSMode() == CMSMode::All) {
+    // For the specific case of longer hue interpolation on a CSS non-repeating
+    // gradient, we have to pretend there is another stop at position=1.0 that
+    // duplicates the last stop, this is probably only used for things like a
+    // color wheel.  No such problem for SVG as it doesn't have that complexity.
+    bool extendLastStop = aMode == wr::ExtendMode::Clamp &&
+                          styleColorInterpolationMethod.hue ==
+                              StyleHueInterpolationMethod::Longer;
     WrColorStopInterpolator interpolator(mStops, styleColorInterpolationMethod,
-                                         aOpacity, aStops);
+                                         aOpacity, aStops, extendLastStop);
     interpolator.CreateStops();
   } else {
     aStops.SetLength(mStops.Length());
diff --git a/layout/painting/nsCSSRenderingGradients.h b/layout/painting/nsCSSRenderingGradients.h
index 549cd8c4b6..68ecab07ae 100644
--- a/layout/painting/nsCSSRenderingGradients.h
+++ b/layout/painting/nsCSSRenderingGradients.h
@@ -44,23 +44,38 @@ class MOZ_STACK_CLASS ColorStopInterpolator {
  public:
   ColorStopInterpolator(
       const nsTArray<ColorStop>& aStops,
-      const StyleColorInterpolationMethod& aStyleColorInterpolationMethod)
+      const StyleColorInterpolationMethod& aStyleColorInterpolationMethod,
+      bool aExtendLastStop)
       : mStyleColorInterpolationMethod(aStyleColorInterpolationMethod),
-        mStops(aStops) {}
+        mStops(aStops),
+        mExtendLastStop(aExtendLastStop) {}
 
   void CreateStops() {
-    for (uint32_t i = 0; i < mStops.Length() - 1; i++) {
+    // This loop intentionally iterates the last stop if extending.
+    uint32_t iterStops = mStops.Length() - (mExtendLastStop ? 0 : 1);
+    for (uint32_t i = 0; i < iterStops; i++) {
+      auto nextindex = i + 1 < mStops.Length() ? i + 1 : i;
       const auto& start = mStops[i];
-      const auto& end = mStops[i + 1];
+      const auto& end = mStops[nextindex];
+      float startPosition = start.mPosition;
+      float endPosition = end.mPosition;
+      // For CSS non-repeating gradients with longer hue specified, we have to
+      // pretend there is a stop beyond the last stop.  This is never the case
+      // on SVG gradients as they only use shorter hue.
+      //
+      // See https://bugzilla.mozilla.org/show_bug.cgi?id=1885716 for more info.
+      if (i == mStops.Length() - 1 && mExtendLastStop) {
+        endPosition = 1.0f;
+      }
       uint32_t extraStops =
-          (uint32_t)(floor(end.mPosition * kFullRangeExtraStops) -
-                     floor(start.mPosition * kFullRangeExtraStops));
+          (uint32_t)(floor(endPosition * kFullRangeExtraStops) -
+                     floor(startPosition * kFullRangeExtraStops));
       extraStops = clamped(extraStops, 1U, kFullRangeExtraStops);
       float step = 1.0f / (float)extraStops;
       for (uint32_t extraStop = 0; extraStop <= extraStops; extraStop++) {
         auto progress = (float)extraStop * step;
         auto position =
-            start.mPosition + progress * (end.mPosition - start.mPosition);
+            startPosition + progress * (endPosition - startPosition);
         StyleAbsoluteColor color =
             Servo_InterpolateColor(mStyleColorInterpolationMethod, &end.mColor,
                                    &start.mColor, progress);
@@ -73,11 +88,15 @@ class MOZ_STACK_CLASS ColorStopInterpolator {
  protected:
   StyleColorInterpolationMethod mStyleColorInterpolationMethod;
   const nsTArray<ColorStop>& mStops;
+  // This indicates that we want to extend the endPosition on the last stop,
+  // which only matters if this is a CSS non-repeating gradient with
+  // StyleHueInterpolationMethod::Longer (only valid for hsl/hwb/lch/oklch).
+  bool mExtendLastStop;
 
-  // this could be made tunable, but at 1.0/128 the error is largely
+  // This could be made tunable, but at 1.0/128 the error is largely
   // irrelevant, as WebRender re-encodes it to 128 pairs of stops.
   //
-  // note that we don't attempt to place the positions of these stops
+  // Note that we don't attempt to place the positions of these stops
   // precisely at intervals, we just add this many extra stops across the
   // range where it is convenient.
   inline static const uint32_t kFullRangeExtraStops = 128;
diff --git a/layout/painting/nsDisplayList.cpp b/layout/painting/nsDisplayList.cpp
index 78388d2185..2c2b7cb04c 100644
--- a/layout/painting/nsDisplayList.cpp
+++ b/layout/painting/nsDisplayList.cpp
@@ -383,6 +383,36 @@ nsDisplayWrapList* nsDisplayListBuilder::MergeItems(
   return merged;
 }
 
+// FIXME(emilio): This whole business should ideally not be needed at all, but
+// there are a variety of hard-to-deal-with caret invalidation issues, like
+// bug 1888583, and caret changes are relatively uncommon, enough that it
+// probably isn't worth chasing all them down.
+void nsDisplayListBuilder::InvalidateCaretFramesIfNeeded() {
+  if (mPaintedCarets.IsEmpty()) {
+    return;
+  }
+  size_t i = mPaintedCarets.Length();
+  while (i--) {
+    nsCaret* caret = mPaintedCarets[i];
+    nsIFrame* oldCaret = caret->GetLastPaintedFrame();
+    nsRect caretRect;
+    nsIFrame* currentCaret = caret->GetPaintGeometry(&caretRect);
+    if (oldCaret == currentCaret) {
+      // Keep tracking this caret, it hasn't changed.
+      continue;
+    }
+    if (oldCaret) {
+      oldCaret->MarkNeedsDisplayItemRebuild();
+    }
+    if (currentCaret) {
+      currentCaret->MarkNeedsDisplayItemRebuild();
+    }
+    // If / when we paint this caret, we'll track it again.
+    caret->SetLastPaintedFrame(nullptr);
+    mPaintedCarets.RemoveElementAt(i);
+  }
+}
+
 void nsDisplayListBuilder::AutoCurrentActiveScrolledRootSetter::
     SetCurrentActiveScrolledRoot(
         const ActiveScrolledRoot* aActiveScrolledRoot) {
@@ -650,7 +680,6 @@ nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
       mCurrentContainerASR(nullptr),
       mCurrentFrame(aReferenceFrame),
       mCurrentReferenceFrame(aReferenceFrame),
-      mCaretFrame(nullptr),
       mScrollInfoItemsForHoisting(nullptr),
       mFirstClipChainToDestroy(nullptr),
       mTableBackgroundSet(nullptr),
@@ -718,21 +747,6 @@ nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
       mRetainingDisplayList && StaticPrefs::layout_display_list_retain_sc();
 }
 
-static PresShell* GetFocusedPresShell() {
-  nsPIDOMWindowOuter* focusedWnd =
-      nsFocusManager::GetFocusManager()->GetFocusedWindow();
-  if (!focusedWnd) {
-    return nullptr;
-  }
-
-  nsCOMPtr<nsIDocShell> focusedDocShell = focusedWnd->GetDocShell();
-  if (!focusedDocShell) {
-    return nullptr;
-  }
-
-  return focusedDocShell->GetPresShell();
-}
-
 void nsDisplayListBuilder::BeginFrame() {
   nsCSSRendering::BeginFrameTreesLocked();
 
@@ -742,26 +756,6 @@ void nsDisplayListBuilder::BeginFrame() {
   mInTransform = false;
   mInFilter = false;
   mSyncDecodeImages = false;
-
-  if (!mBuildCaret) {
-    return;
-  }
-
-  RefPtr<PresShell> presShell = GetFocusedPresShell();
-  if (presShell) {
-    RefPtr<nsCaret> caret = presShell->GetCaret();
-    mCaretFrame = caret->GetPaintGeometry(&mCaretRect);
-
-    // The focused pres shell may not be in the document that we're
-    // painting, or be in a popup. Check if the display root for
-    // the caret matches the display root that we're painting, and
-    // only use it if it matches.
-    if (mCaretFrame &&
-        nsLayoutUtils::GetDisplayRootFrame(mCaretFrame) !=
-            nsLayoutUtils::GetDisplayRootFrame(mReferenceFrame)) {
-      mCaretFrame = nullptr;
-    }
-  }
 }
 
 void nsDisplayListBuilder::AddEffectUpdate(dom::RemoteBrowser* aBrowser,
@@ -801,7 +795,6 @@ void nsDisplayListBuilder::EndFrame() {
   FreeClipChains();
   FreeTemporaryItems();
   nsCSSRendering::EndFrameTreesLocked();
-  mCaretFrame = nullptr;
 }
 
 void nsDisplayListBuilder::MarkFrameForDisplay(nsIFrame* aFrame,
@@ -1141,12 +1134,32 @@ void nsDisplayListBuilder::EnterPresShell(const nsIFrame* aReferenceFrame,
     return;
   }
 
-  // Caret frames add visual area to their frame, but we don't update the
-  // overflow area. Use flags to make sure we build display items for that frame
-  // instead.
-  if (mCaretFrame && mCaretFrame->PresShell() == state->mPresShell) {
-    MarkFrameForDisplay(mCaretFrame, aReferenceFrame);
-  }
+  state->mCaretFrame = [&]() -> nsIFrame* {
+    RefPtr<nsCaret> caret = state->mPresShell->GetCaret();
+    nsIFrame* currentCaret = caret->GetPaintGeometry(&mCaretRect);
+    if (!currentCaret) {
+      return nullptr;
+    }
+
+    // Check if the display root for the caret matches the display root that
+    // we're painting, and only use it if it matches. Likely we only need this
+    // for carets inside popups.
+    if (nsLayoutUtils::GetDisplayRootFrame(currentCaret) !=
+        nsLayoutUtils::GetDisplayRootFrame(aReferenceFrame)) {
+      return nullptr;
+    }
+
+    // Caret frames add visual area to their frame, but we don't update the
+    // overflow area. Use flags to make sure we build display items for that
+    // frame instead.
+    MOZ_ASSERT(currentCaret->PresShell() == state->mPresShell);
+    MarkFrameForDisplay(currentCaret, aReferenceFrame);
+    caret->SetLastPaintedFrame(currentCaret);
+    if (!mPaintedCarets.Contains(caret)) {
+      mPaintedCarets.AppendElement(std::move(caret));
+    }
+    return currentCaret;
+  }();
 }
 
 // A non-blank paint is a paint that does not just contain the canvas
@@ -2534,9 +2547,7 @@ struct ZSortItem {
 };
 
 struct ZOrderComparator {
-  bool operator()(const ZSortItem& aLeft, const ZSortItem& aRight) const {
-    // Note that we can't just take the difference of the two
-    // z-indices here, because that might overflow a 32-bit int.
+  bool LessThan(const ZSortItem& aLeft, const ZSortItem& aRight) const {
     return aLeft.zIndex < aRight.zIndex;
   }
 };
@@ -2549,7 +2560,7 @@ struct ContentComparator {
   explicit ContentComparator(nsIContent* aCommonAncestor)
       : mCommonAncestor(aCommonAncestor) {}
 
-  bool operator()(nsDisplayItem* aLeft, nsDisplayItem* aRight) const {
+  bool LessThan(nsDisplayItem* aLeft, nsDisplayItem* aRight) const {
     // It's possible that the nsIContent for aItem1 or aItem2 is in a
     // subdocument of commonAncestor, because display items for subdocuments
     // have been mixed into the same list. Ensure that we're looking at content
@@ -2562,7 +2573,8 @@ struct ContentComparator {
       // Something weird going on
       return true;
     }
-    return nsContentUtils::CompareTreePosition<TreeKind::Flat>(
+    return content1 != content2 &&
+           nsContentUtils::CompareTreePosition<TreeKind::Flat>(
                content1, content2, mCommonAncestor) < 0;
   }
 };
@@ -4134,8 +4146,7 @@ bool nsDisplayCaret::CreateWebRenderCommands(
   nscolor caretColor;
   nsIFrame* frame =
       mCaret->GetPaintGeometry(&caretRect, &hookRect, &caretColor);
-  MOZ_ASSERT(frame == mFrame, "We're referring different frame");
-  if (!frame) {
+  if (NS_WARN_IF(!frame) || NS_WARN_IF(frame != mFrame)) {
     return true;
   }
 
diff --git a/layout/painting/nsDisplayList.h b/layout/painting/nsDisplayList.h
index 5064677cc7..acda6ea863 100644
--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -659,7 +659,7 @@ class nsDisplayListBuilder {
    * Get the frame that the caret is supposed to draw in.
    * If the caret is currently invisible, this will be null.
    */
-  nsIFrame* GetCaretFrame() { return mCaretFrame; }
+  nsIFrame* GetCaretFrame() { return CurrentPresShellState()->mCaretFrame; }
   /**
    * Get the rectangle we're supposed to draw the caret into.
    */
@@ -852,9 +852,9 @@ class nsDisplayListBuilder {
   /**
    * Notifies the builder that a particular themed widget exists
    * at the given rectangle within the currently built display list.
-   * For certain appearance values (currently only StyleAppearance::Toolbar and
-   * StyleAppearance::WindowTitlebar) this gets called during every display list
-   * construction, for every themed widget of the right type within the
+   * For certain appearance values (currently only
+   * StyleAppearance::MozWindowTitlebar) this gets called during every display
+   * list construction, for every themed widget of the right type within the
    * display list, except for themed widgets which are transformed or have
    * effects applied to them (e.g. CSS opacity or filters).
    *
@@ -904,6 +904,11 @@ class nsDisplayListBuilder {
                        const dom::EffectsInfo& aUpdate);
 
   /**
+   * Invalidates the caret frames from previous paints, if they have changed.
+   */
+  void InvalidateCaretFramesIfNeeded();
+
+  /**
    * Allocate memory in our arena. It will only be freed when this display list
    * builder is destroyed. This memory holds nsDisplayItems and
    * DisplayItemClipChain objects.
@@ -1729,6 +1734,7 @@ class nsDisplayListBuilder {
     bool mInsidePointerEventsNoneDoc;
     bool mTouchEventPrefEnabledDoc;
     nsIFrame* mPresShellIgnoreScrollFrame;
+    nsIFrame* mCaretFrame = nullptr;
   };
 
   PresShellState* CurrentPresShellState() {
@@ -1763,7 +1769,6 @@ class nsDisplayListBuilder {
   // The reference frame for mCurrentFrame.
   const nsIFrame* mCurrentReferenceFrame;
 
-  nsIFrame* mCaretFrame;
   // A temporary list that we append scroll info items to while building
   // display items for the contents of frames with SVG effects.
   // Only non-null when ShouldBuildScrollInfoItemsForHoisting() is true.
@@ -1808,6 +1813,9 @@ class nsDisplayListBuilder {
   // Stores reusable items collected during display list preprocessing.
   nsTHashSet<nsDisplayItem*> mReuseableItems;
 
+  // Tracked carets used for retained display list.
+  AutoTArray<RefPtr<nsCaret>, 1> mPaintedCarets;
+
   // Tracked regions used for retained display list.
   WeakFrameRegion mRetainedWindowDraggingRegion;
   WeakFrameRegion mRetainedWindowNoDraggingRegion;
@@ -3195,12 +3203,13 @@ class nsDisplayList {
     // array of 20 items should be able to avoid a lot of dynamic allocations
     // here.
     AutoTArray<Item, 20> items;
+    // Ensure we need just one alloc otherwise, no-op if enough.
+    items.SetCapacity(Length());
 
     for (nsDisplayItem* item : TakeItems()) {
       items.AppendElement(Item(item));
     }
-
-    std::stable_sort(items.begin(), items.end(), aComparator);
+    items.StableSort(aComparator);
 
     for (Item& item : items) {
       AppendToTop(item);
@@ -3208,6 +3217,7 @@ class nsDisplayList {
   }
 
   nsDisplayList TakeItems() {
+    // This std::move makes this a defined empty list, see assignment operator.
     nsDisplayList list = std::move(*this);
 #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
     list.mAllowNonEmptyDestruction = true;
diff --git a/layout/reftests/bidi/dirAuto/reftest.list b/layout/reftests/bidi/dirAuto/reftest.list
index f47c635124..5fc24b2a2b 100644
--- a/layout/reftests/bidi/dirAuto/reftest.list
+++ b/layout/reftests/bidi/dirAuto/reftest.list
@@ -42,7 +42,7 @@
 == dynamicDirAuto-setLTR-InvalidDir5.html dynamicDirAuto-refLTR-LTR.html
 == dynamicDirAuto-setLTR-InvalidDir6.html dynamicDirAuto-refLTR-LTR.html
 == dynamicDirAuto-setLTR-InvalidDir7.html dynamicDirAuto-refLTR-LTR.html
-== dynamicDirAuto-setLTR-InvalidDir7.html dynamicDirAuto-refLTR-LTR.html
+== dynamicDirAuto-setLTR-InvalidDir8.html dynamicDirAuto-refLTR-LTR.html
 == dynamicDirAuto-setRTL-Auto1.html dynamicDirAuto-refRTL-RTL.html
 fuzzy-if(Android,0-1,0-1) == dynamicDirAuto-setRTL-Auto2.html dynamicDirAuto-refRTL-RTL.html # android fuzz: bug 1461573
 == dynamicDirAuto-setRTL-Auto3.html dynamicDirAuto-refRTL-RTL.html
diff --git a/layout/reftests/bugs/1888941-text-transform-emergency-wrap-ref.html b/layout/reftests/bugs/1888941-text-transform-emergency-wrap-ref.html
new file mode 100644
index 0000000000..1ae7db9050
--- /dev/null
+++ b/layout/reftests/bugs/1888941-text-transform-emergency-wrap-ref.html
@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+<div>12345-<br>67890-<br>98765-<br>43210</div>
diff --git a/layout/reftests/bugs/1888941-text-transform-emergency-wrap.html b/layout/reftests/bugs/1888941-text-transform-emergency-wrap.html
new file mode 100644
index 0000000000..9e7c49cf57
--- /dev/null
+++ b/layout/reftests/bugs/1888941-text-transform-emergency-wrap.html
@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+<div style="width: 1px; text-transform: uppercase">12345-67890-98765-43210</div>
diff --git a/layout/reftests/bugs/307102-2-ref.html b/layout/reftests/bugs/307102-2-ref.html
deleted file mode 100644
index 8b72bc0383..0000000000
--- a/layout/reftests/bugs/307102-2-ref.html
+++ /dev/null
@@ -1,8 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <body>
-    <div style="position: absolute; width: 100px;">
-      <input style="position: absolute; top: 0; left: 0;">
-    </div>
-  </body>
-</html>
diff --git a/layout/reftests/bugs/307102-2.html b/layout/reftests/bugs/307102-2.html
deleted file mode 100644
index cfeb6658a9..0000000000
--- a/layout/reftests/bugs/307102-2.html
+++ /dev/null
@@ -1,8 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <body>
-    <div style="position: absolute; width: 100px;">
-      <input style="position: absolute; top: 0; left: 0; right: 0">
-    </div>
-  </body>
-</html>
diff --git a/layout/reftests/bugs/385870-1-ref.html b/layout/reftests/bugs/385870-1-ref.html
deleted file mode 100644
index fcebd34fb2..0000000000
--- a/layout/reftests/bugs/385870-1-ref.html
+++ /dev/null
@@ -1,51 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-<title></title>
-<style>
-#red {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  left: 10px;
-}
-
-#green {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  width: 80px;
-  right: 10px;
-}
-
-#blue {
-  position: absolute;
-  background-color: blue;
-  left: 10px;
-  height: 80px;
-  bottom: 10px;
-}
-
-#yellow {
-  position: absolute;
-  background-color: blue;
-  right: 10px;
-  width: 80px;
-  height: 80px;
-  bottom: 10px;
-}
-
-</style>
-<script>
-
-</script>
-</head>
-<body>
-
-<textarea id=red></textarea>
-<textarea id=green></textarea>
-<textarea id=blue></textarea>
-<textarea id=yellow></textarea>
-
-</body>
-</html>
diff --git a/layout/reftests/bugs/385870-1.html b/layout/reftests/bugs/385870-1.html
deleted file mode 100644
index 4d292e1c20..0000000000
--- a/layout/reftests/bugs/385870-1.html
+++ /dev/null
@@ -1,55 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-<title></title>
-<style>
-#red {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  left: 10px;
-  right: 100px;
-  bottom: 100px;
-}
-
-#green {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  width: 80px;
-  right: 10px;
-  bottom: 100px;
-}
-
-#blue {
-  position: absolute;
-  background-color: blue;
-  left: 10px;
-  height: 80px;
-  right: 100px;
-  bottom: 10px;
-}
-
-#yellow {
-  position: absolute;
-  background-color: blue;
-  right: 10px;
-  width: 80px;
-  height: 80px;
-  bottom: 10px;
-}
-
-</style>
-<script>
-
-</script>
-</head>
-<body>
-
-<textarea id=red></textarea>
-<textarea id=green></textarea>
-<textarea id=blue></textarea>
-<textarea id=yellow></textarea>
-
-</body>
-</html>
diff --git a/layout/reftests/bugs/385870-2-ref.html b/layout/reftests/bugs/385870-2-ref.html
deleted file mode 100644
index eebef3805e..0000000000
--- a/layout/reftests/bugs/385870-2-ref.html
+++ /dev/null
@@ -1,51 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-<title></title>
-<style>
-#red {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  left: 10px;
-}
-
-#green {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  width: 80px;
-  right: 10px;
-}
-
-#blue {
-  position: absolute;
-  background-color: blue;
-  left: 10px;
-  height: 80px;
-  bottom: 10px;
-}
-
-#yellow {
-  position: absolute;
-  background-color: blue;
-  right: 10px;
-  width: 80px;
-  height: 80px;
-  bottom: 10px;
-}
-
-</style>
-<script>
-
-</script>
-</head>
-<body>
-
-<input id=red>
-<input id=green>
-<input id=blue>
-<input id=yellow>
-
-</body>
-</html>
diff --git a/layout/reftests/bugs/385870-2.html b/layout/reftests/bugs/385870-2.html
deleted file mode 100644
index c641abb796..0000000000
--- a/layout/reftests/bugs/385870-2.html
+++ /dev/null
@@ -1,55 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-<title></title>
-<style>
-#red {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  left: 10px;
-  right: 100px;
-  bottom: 100px;
-}
-
-#green {
-  position: absolute;
-  background-color: blue;
-  top: 10px;
-  width: 80px;
-  right: 10px;
-  bottom: 100px;
-}
-
-#blue {
-  position: absolute;
-  background-color: blue;
-  left: 10px;
-  height: 80px;
-  right: 100px;
-  bottom: 10px;
-}
-
-#yellow {
-  position: absolute;
-  background-color: blue;
-  right: 10px;
-  width: 80px;
-  height: 80px;
-  bottom: 10px;
-}
-
-</style>
-<script>
-
-</script>
-</head>
-<body>
-
-<input id=red>
-<input id=green>
-<input id=blue>
-<input id=yellow>
-
-</body>
-</html>
diff --git a/layout/reftests/bugs/404553-1-ref.html b/layout/reftests/bugs/404553-1-ref.html
index cfa0dc8147..ac35a9e4b5 100644
--- a/layout/reftests/bugs/404553-1-ref.html
+++ b/layout/reftests/bugs/404553-1-ref.html
@@ -1 +1 @@
-<div style="background-color: lime; height: 50px;"><div style="background: green; width: 50px; margin-left: auto; margin-right: 0;">&nbsp;</div></div>
\ No newline at end of file
+<div style="background-color: lime; height: 50px;"><div style="background: green; width: 50px;">&nbsp;</div></div>
diff --git a/layout/reftests/bugs/404553-1.html b/layout/reftests/bugs/404553-1.html
index 692c63c67c..ab63f1396e 100644
--- a/layout/reftests/bugs/404553-1.html
+++ b/layout/reftests/bugs/404553-1.html
@@ -1 +1 @@
-<table><marquee behavior="alternate" scrollamount="0" style="background-color: lime; height: 50px;"><div style="background: green; width: 50px">&nbsp;</div></marquee><span><title>
\ No newline at end of file
+<table><marquee behavior="alternate" scrollamount="0" style="background-color: lime; height: 50px;"><div style="background: green; width: 50px">&nbsp;</div></marquee><span><title>
diff --git a/layout/reftests/bugs/reftest.list b/layout/reftests/bugs/reftest.list
index d85d5e7310..28e96a51da 100644
--- a/layout/reftests/bugs/reftest.list
+++ b/layout/reftests/bugs/reftest.list
@@ -342,8 +342,7 @@ skip-if(useDrawSnapshot) == 306660-2.html 306660-2-ref.html
 == 306660-3.html 306660-3-ref.html
 == 307076-1.html 307076-1-ref.html
 == 307102-1.html 307102-1-ref.html
-== 307102-2.html 307102-2-ref.html
-== 307102-3.html 307102-3-ref.html
+random == 307102-3.html 307102-3-ref.html
 == 307102-4.html 307102-4-ref.html
 == 308406-1.html 308406-1-ref.html
 == 308406-2.html 308406-2-ref.html
@@ -725,8 +724,6 @@ fuzzy(0-2,0-5) == 381507-1.html 381507-1-ref.html
 fuzzy(0-1,0-600) == 385823-2a.html 385823-2-ref.html
 fails == 385823-2b.html 385823-2-ref.html
 fuzzy(0-1,0-600) == 385823-2c.html 385823-2-ref.html
-fuzzy(0-2,0-11) == 385870-1.html 385870-1-ref.html
-fuzzy(0-2,0-3) == 385870-2.html 385870-2-ref.html
 == 386014-1a.html 386014-1-ref.html
 == 386014-1b.html 386014-1-ref.html
 == 386014-1c.html 386014-1-ref.html
@@ -2165,3 +2162,4 @@ fuzzy-if(!useDrawSnapshot,18-19,294-322) == 1840747-1.html about:blank
 # here. That's tracked in bug 1840747.
 fuzzy-if(!useDrawSnapshot&&!swgl,254-255,110-121) fuzzy-if(useDrawSnapshot,18-18,93-93) fuzzy-if(swgl,19-19,58-58) == 1841355-1.html about:blank
 skip-if(((AddressSanitizer||ThreadSanitizer)&&gtkWidget)||(isDebugBuild&&Android)) fuzzy(0-123,0-1425) == 1878294-1.html 1878294-1-ref.html
+== 1888941-text-transform-emergency-wrap.html 1888941-text-transform-emergency-wrap-ref.html
diff --git a/layout/reftests/counters/counter-hebrew-reference.html b/layout/reftests/counters/counter-hebrew-reference.html
index f2c1326056..0d08f6d49b 100644
--- a/layout/reftests/counters/counter-hebrew-reference.html
+++ b/layout/reftests/counters/counter-hebrew-reference.html
@@ -55,10 +55,7 @@
    <span>&#x5d8;&#x05f3;</span>
    <span>&#x5d8;&#x05f3;&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;</span>
    <span>&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;&#x05f3;&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;</span>
-   <style>
-     #c18:before { counter-set: c 18; content: counter(c, hebrew); }
-   </style>
-   <span id="c18"></span>
+   <span>1000000</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/counters-hebrew-reference.html b/layout/reftests/counters/counters-hebrew-reference.html
index 7e725760e8..9ae6b5e011 100644
--- a/layout/reftests/counters/counters-hebrew-reference.html
+++ b/layout/reftests/counters/counters-hebrew-reference.html
@@ -12,54 +12,51 @@
  <p></p>
  <div>
    <span>&#x5d0;.&#x5d0;</span>
-   <span>&#x5d1;</span>
-   <span>&#x5d2;</span>
-   <span>&#x5d3;</span>
-   <span>&#x5d4;</span>
-   <span>&#x5d5;</span>
-   <span>&#x5d6;</span>
-   <span>&#x5d7;</span>
-   <span>&#x5d8;</span>
-   <span>&#x5d9;</span>
-   <span>&#x5d9;&#x5d0;</span>
-   <span>&#x5d9;&#x5d1;</span>
-   <span>&#x5d9;&#x5d2;</span>
-   <span>&#x5d9;&#x5d3;</span>
-   <span>&#x5d8;&#x5d5;</span>
-   <span>&#x5d8;&#x5d6;</span>
-   <span>&#x5d9;&#x5d6;</span>
-   <span>&#x5d9;&#x5d6;.&#x5db;</span>
-   <span>&#x5d9;&#x5d6;.&#x5dc;</span>
-   <span>&#x5d9;&#x5d6;.&#x5de;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e0;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e1;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e2;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e4;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e6;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e7;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e8;</span>
-   <span>&#x5d9;&#x5d6;.&#x5e9;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;&#x5e7;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;&#x5e8;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;&#x5e9;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;&#x5ea;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;&#x5ea;&#x5e7;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d0;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d1;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d2;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d3;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d4;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d5;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d6;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d7;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d8;&#x05f3;</span>
-   <span>&#x5d9;&#x5d6;.&#x5d8;&#x05f3;&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;</span>
-   <span>&#x5d9;&#x5d6;.&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;&#x05f3;&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;</span>
-   <style>
-     #c18:before { counter-set: c 18; content: counter(c, hebrew); }
-   </style>
-   <span id="c18"></span>
+   <span>&#x5d0;.&#x5d1;</span>
+   <span>&#x5d0;.&#x5d2;</span>
+   <span>&#x5d0;.&#x5d3;</span>
+   <span>&#x5d0;.&#x5d4;</span>
+   <span>&#x5d0;.&#x5d5;</span>
+   <span>&#x5d0;.&#x5d6;</span>
+   <span>&#x5d0;.&#x5d7;</span>
+   <span>&#x5d0;.&#x5d8;</span>
+   <span>&#x5d0;.&#x5d9;</span>
+   <span>&#x5d0;.&#x5d9;&#x5d0;</span>
+   <span>&#x5d0;.&#x5d9;&#x5d1;</span>
+   <span>&#x5d0;.&#x5d9;&#x5d2;</span>
+   <span>&#x5d0;.&#x5d9;&#x5d3;</span>
+   <span>&#x5d0;.&#x5d8;&#x5d5;</span>
+   <span>&#x5d0;.&#x5d8;&#x5d6;</span>
+   <span>&#x5d0;.&#x5d9;&#x5d6;</span>
+   <span>&#x5d0;.&#x5db;</span>
+   <span>&#x5d0;.&#x5dc;</span>
+   <span>&#x5d0;.&#x5de;</span>
+   <span>&#x5d0;.&#x5e0;</span>
+   <span>&#x5d0;.&#x5e1;</span>
+   <span>&#x5d0;.&#x5e2;</span>
+   <span>&#x5d0;.&#x5e4;</span>
+   <span>&#x5d0;.&#x5e6;</span>
+   <span>&#x5d0;.&#x5e7;</span>
+   <span>&#x5d0;.&#x5e8;</span>
+   <span>&#x5d0;.&#x5e9;</span>
+   <span>&#x5d0;.&#x5ea;</span>
+   <span>&#x5d0;.&#x5ea;&#x5e7;</span>
+   <span>&#x5d0;.&#x5ea;&#x5e8;</span>
+   <span>&#x5d0;.&#x5ea;&#x5e9;</span>
+   <span>&#x5d0;.&#x5ea;&#x5ea;</span>
+   <span>&#x5d0;.&#x5ea;&#x5ea;&#x5e7;</span>
+   <span>&#x5d0;.&#x5d0;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d1;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d2;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d3;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d4;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d5;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d6;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d7;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d8;&#x05f3;</span>
+   <span>&#x5d0;.&#x5d8;&#x05f3;&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;</span>
+   <span>&#x5d0;.&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;&#x05f3;&#x5ea;&#x5ea;&#x5e7;&#x5e6;&#x5d8;</span>
+   <span>&#x5d0;.1000000</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counter-06-b-reference.html b/layout/reftests/counters/t1202-counter-06-b-reference.html
index 78c9300a8b..0fdc2905e2 100644
--- a/layout/reftests/counters/t1202-counter-06-b-reference.html
+++ b/layout/reftests/counters/t1202-counter-06-b-reference.html
@@ -24,8 +24,8 @@
    <span>11</span>
    <span>12</span>
    <span>99</span>
-   <span>13</span>
-   <span>14</span>
+   <span>100</span>
+   <span>101</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counter-07-b-reference.html b/layout/reftests/counters/t1202-counter-07-b-reference.html
index b0da1fa597..f6429c211a 100644
--- a/layout/reftests/counters/t1202-counter-07-b-reference.html
+++ b/layout/reftests/counters/t1202-counter-07-b-reference.html
@@ -23,12 +23,12 @@
    <span>xi</span>
    <span>xii</span>
    <span>xlix</span>
-   <span>xiii</span>
+   <span>l</span>
    <span>ccclxxxix</span>
-   <span>xiv</span>
+   <span>cccxc</span>
    <span>mmmcdlxxxix</span>
-   <span>xv</span>
-   <span>xvi</span>
+   <span>mmmcdxc</span>
+   <span>mmmcdxci</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counter-08-b-reference.html b/layout/reftests/counters/t1202-counter-08-b-reference.html
index 40a8bf8d53..16be49dcbc 100644
--- a/layout/reftests/counters/t1202-counter-08-b-reference.html
+++ b/layout/reftests/counters/t1202-counter-08-b-reference.html
@@ -23,12 +23,12 @@
    <span>XI</span>
    <span>XII</span>
    <span>XLIX</span>
-   <span>XIII</span>
+   <span>L</span>
    <span>CCCLXXXIX</span>
-   <span>XIV</span>
+   <span>CCCXC</span>
    <span>MMMCDLXXXIX</span>
-   <span>XV</span>
-   <span>XVI</span>
+   <span>MMMCDXC</span>
+   <span>MMMCDXCI</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counters-06-b-reference.html b/layout/reftests/counters/t1202-counters-06-b-reference.html
index 7b3af2409f..b2b5ca1a07 100644
--- a/layout/reftests/counters/t1202-counters-06-b-reference.html
+++ b/layout/reftests/counters/t1202-counters-06-b-reference.html
@@ -13,20 +13,20 @@
 
  <div>
    <span>01.01</span>
-   <span>02</span>
-   <span>03</span>
-   <span>04</span>
-   <span>05</span>
-   <span>06</span>
-   <span>07</span>
-   <span>08</span>
-   <span>09</span>
-   <span>10</span>
-   <span>11</span>
-   <span>12</span>
-   <span>12.99</span>
-   <span>13</span>
-   <span>14</span>
+   <span>01.02</span>
+   <span>01.03</span>
+   <span>01.04</span>
+   <span>01.05</span>
+   <span>01.06</span>
+   <span>01.07</span>
+   <span>01.08</span>
+   <span>01.09</span>
+   <span>01.10</span>
+   <span>01.11</span>
+   <span>01.12</span>
+   <span>01.99</span>
+   <span>01.100</span>
+   <span>01.101</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counters-07-b-reference.html b/layout/reftests/counters/t1202-counters-07-b-reference.html
index 49713c7344..ef08cfbefc 100644
--- a/layout/reftests/counters/t1202-counters-07-b-reference.html
+++ b/layout/reftests/counters/t1202-counters-07-b-reference.html
@@ -13,24 +13,24 @@
 
  <div>
    <span>i.i</span>
-   <span>ii</span>
-   <span>iii</span>
-   <span>iv</span>
-   <span>v</span>
-   <span>vi</span>
-   <span>vii</span>
-   <span>viii</span>
-   <span>ix</span>
-   <span>x</span>
-   <span>xi</span>
-   <span>xii</span>
-   <span>xii.xlix</span>
-   <span>xiii</span>
-   <span>xiii.ccclxxxix</span>
-   <span>xiv</span>
-   <span>xiv.mmmcdlxxxix</span>
-   <span>xv</span>
-   <span>xvi</span>
+   <span>i.ii</span>
+   <span>i.iii</span>
+   <span>i.iv</span>
+   <span>i.v</span>
+   <span>i.vi</span>
+   <span>i.vii</span>
+   <span>i.viii</span>
+   <span>i.ix</span>
+   <span>i.x</span>
+   <span>i.xi</span>
+   <span>i.xii</span>
+   <span>i.xlix</span>
+   <span>i.l</span>
+   <span>i.ccclxxxix</span>
+   <span>i.cccxc</span>
+   <span>i.mmmcdlxxxix</span>
+   <span>i.mmmcdxc</span>
+   <span>i.mmmcdxci</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counters-08-b-reference.html b/layout/reftests/counters/t1202-counters-08-b-reference.html
index 92a6429164..7838d10fbb 100644
--- a/layout/reftests/counters/t1202-counters-08-b-reference.html
+++ b/layout/reftests/counters/t1202-counters-08-b-reference.html
@@ -13,24 +13,24 @@
 
  <div>
    <span>I.I</span>
-   <span>II</span>
-   <span>III</span>
-   <span>IV</span>
-   <span>V</span>
-   <span>VI</span>
-   <span>VII</span>
-   <span>VIII</span>
-   <span>IX</span>
-   <span>X</span>
-   <span>XI</span>
-   <span>XII</span>
-   <span>XII.XLIX</span>
-   <span>XIII</span>
-   <span>XIII.CCCLXXXIX</span>
-   <span>XIV</span>
-   <span>XIV.MMMCDLXXXIX</span>
-   <span>XV</span>
-   <span>XVI</span>
+   <span>I.II</span>
+   <span>I.III</span>
+   <span>I.IV</span>
+   <span>I.V</span>
+   <span>I.VI</span>
+   <span>I.VII</span>
+   <span>I.VIII</span>
+   <span>I.IX</span>
+   <span>I.X</span>
+   <span>I.XI</span>
+   <span>I.XII</span>
+   <span>I.XLIX</span>
+   <span>I.L</span>
+   <span>I.CCCLXXXIX</span>
+   <span>I.CCCXC</span>
+   <span>I.MMMCDLXXXIX</span>
+   <span>I.MMMCDXC</span>
+   <span>I.MMMCDXCI</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counters-09-b-reference.html b/layout/reftests/counters/t1202-counters-09-b-reference.html
index 928e440ae1..0511df55e4 100644
--- a/layout/reftests/counters/t1202-counters-09-b-reference.html
+++ b/layout/reftests/counters/t1202-counters-09-b-reference.html
@@ -13,45 +13,45 @@
 
  <div>
    <span>&#x10D0;.&#x10D0;</span>
-   <span>&#x10D1;</span>
-   <span>&#x10D2;</span>
-   <span>&#x10D3;</span>
-   <span>&#x10D4;</span>
-   <span>&#x10D5;</span>
-   <span>&#x10D6;</span>
-   <span>&#x10F1;</span>
-   <span>&#x10D7;</span>
-   <span>&#x10D8;</span>
-   <span>&#x10D8;&#x10D0;</span>
-   <span>&#x10D8;&#x10D1;</span>
-   <span>&#x10D8;&#x10D1;.&#x10D9;</span>
-   <span>&#x10D8;&#x10D1;.&#x10DA;</span>
-   <span>&#x10D8;&#x10D1;.&#x10DB;</span>
-   <span>&#x10D8;&#x10D1;.&#x10DC;</span>
-   <span>&#x10D8;&#x10D1;.&#x10F2;</span>
-   <span>&#x10D8;&#x10D1;.&#x10DD;</span>
-   <span>&#x10D8;&#x10D1;.&#x10DE;</span>
-   <span>&#x10D8;&#x10D1;.&#x10DF;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E0;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E1;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E2;</span>
-   <span>&#x10D8;&#x10D1;.&#x10F3;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E4;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E5;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E6;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E7;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E8;</span>
-   <span>&#x10D8;&#x10D1;.&#x10E9;</span>
-   <span>&#x10D8;&#x10D1;.&#x10EA;</span>
-   <span>&#x10D8;&#x10D1;.&#x10EB;</span>
-   <span>&#x10D8;&#x10D1;.&#x10EC;</span>
-   <span>&#x10D8;&#x10D1;.&#x10ED;</span>
-   <span>&#x10D8;&#x10D1;.&#x10EE;</span>
-   <span>&#x10D8;&#x10D1;.&#x10F4;</span>
-   <span>&#x10D8;&#x10D1;.&#x10EF;</span>
-   <span>&#x10D8;&#x10D1;.&#x10F0;</span>
-   <span>&#x10D8;&#x10D1;.&#x10F5;</span>
-   <span>&#x10D8;&#x10D1;.&#x10F5;&#x10F0;&#x10E8;&#x10DF;&#x10D7;</span>
+   <span>&#x10D0;.&#x10D1;</span>
+   <span>&#x10D0;.&#x10D2;</span>
+   <span>&#x10D0;.&#x10D3;</span>
+   <span>&#x10D0;.&#x10D4;</span>
+   <span>&#x10D0;.&#x10D5;</span>
+   <span>&#x10D0;.&#x10D6;</span>
+   <span>&#x10D0;.&#x10F1;</span>
+   <span>&#x10D0;.&#x10D7;</span>
+   <span>&#x10D0;.&#x10D8;</span>
+   <span>&#x10D0;.&#x10D8;&#x10D0;</span>
+   <span>&#x10D0;.&#x10D8;&#x10D1;</span>
+   <span>&#x10D0;.&#x10D9;</span>
+   <span>&#x10D0;.&#x10DA;</span>
+   <span>&#x10D0;.&#x10DB;</span>
+   <span>&#x10D0;.&#x10DC;</span>
+   <span>&#x10D0;.&#x10F2;</span>
+   <span>&#x10D0;.&#x10DD;</span>
+   <span>&#x10D0;.&#x10DE;</span>
+   <span>&#x10D0;.&#x10DF;</span>
+   <span>&#x10D0;.&#x10E0;</span>
+   <span>&#x10D0;.&#x10E1;</span>
+   <span>&#x10D0;.&#x10E2;</span>
+   <span>&#x10D0;.&#x10F3;</span>
+   <span>&#x10D0;.&#x10E4;</span>
+   <span>&#x10D0;.&#x10E5;</span>
+   <span>&#x10D0;.&#x10E6;</span>
+   <span>&#x10D0;.&#x10E7;</span>
+   <span>&#x10D0;.&#x10E8;</span>
+   <span>&#x10D0;.&#x10E9;</span>
+   <span>&#x10D0;.&#x10EA;</span>
+   <span>&#x10D0;.&#x10EB;</span>
+   <span>&#x10D0;.&#x10EC;</span>
+   <span>&#x10D0;.&#x10ED;</span>
+   <span>&#x10D0;.&#x10EE;</span>
+   <span>&#x10D0;.&#x10F4;</span>
+   <span>&#x10D0;.&#x10EF;</span>
+   <span>&#x10D0;.&#x10F0;</span>
+   <span>&#x10D0;.&#x10F5;</span>
+   <span>&#x10D0;.&#x10F5;&#x10F0;&#x10E8;&#x10DF;&#x10D7;</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1202-counters-10-b-reference.html b/layout/reftests/counters/t1202-counters-10-b-reference.html
index f3a3fa6dfa..af593dab5c 100644
--- a/layout/reftests/counters/t1202-counters-10-b-reference.html
+++ b/layout/reftests/counters/t1202-counters-10-b-reference.html
@@ -13,44 +13,44 @@
 
  <div>
    <span>&#x531;.&#x531;</span>
-   <span>&#x532;</span>
-   <span>&#x533;</span>
-   <span>&#x534;</span>
-   <span>&#x535;</span>
-   <span>&#x536;</span>
-   <span>&#x537;</span>
-   <span>&#x538;</span>
-   <span>&#x539;</span>
-   <span>&#x53A;</span>
-   <span>&#x53A;&#x531;</span>
-   <span>&#x53A;&#x532;</span>
-   <span>&#x53A;&#x532;.&#x53B;</span>
-   <span>&#x53A;&#x532;.&#x53C;</span>
-   <span>&#x53A;&#x532;.&#x53D;</span>
-   <span>&#x53A;&#x532;.&#x53E;</span>
-   <span>&#x53A;&#x532;.&#x53F;</span>
-   <span>&#x53A;&#x532;.&#x540;</span>
-   <span>&#x53A;&#x532;.&#x541;</span>
-   <span>&#x53A;&#x532;.&#x542;</span>
-   <span>&#x53A;&#x532;.&#x543;</span>
-   <span>&#x53A;&#x532;.&#x544;</span>
-   <span>&#x53A;&#x532;.&#x545;</span>
-   <span>&#x53A;&#x532;.&#x546;</span>
-   <span>&#x53A;&#x532;.&#x547;</span>
-   <span>&#x53A;&#x532;.&#x548;</span>
-   <span>&#x53A;&#x532;.&#x549;</span>
-   <span>&#x53A;&#x532;.&#x54A;</span>
-   <span>&#x53A;&#x532;.&#x54B;</span>
-   <span>&#x53A;&#x532;.&#x54C;</span>
-   <span>&#x53A;&#x532;.&#x54D;</span>
-   <span>&#x53A;&#x532;.&#x54E;</span>
-   <span>&#x53A;&#x532;.&#x54F;</span>
-   <span>&#x53A;&#x532;.&#x550;</span>
-   <span>&#x53A;&#x532;.&#x551;</span>
-   <span>&#x53A;&#x532;.&#x552;</span>
-   <span>&#x53A;&#x532;.&#x553;</span>
-   <span>&#x53A;&#x532;.&#x554;</span>
-   <span>&#x53A;&#x532;.&#x554;&#x54B;&#x542;&#x539;</span>
+   <span>&#x531;.&#x532;</span>
+   <span>&#x531;.&#x533;</span>
+   <span>&#x531;.&#x534;</span>
+   <span>&#x531;.&#x535;</span>
+   <span>&#x531;.&#x536;</span>
+   <span>&#x531;.&#x537;</span>
+   <span>&#x531;.&#x538;</span>
+   <span>&#x531;.&#x539;</span>
+   <span>&#x531;.&#x53A;</span>
+   <span>&#x531;.&#x53A;&#x531;</span>
+   <span>&#x531;.&#x53A;&#x532;</span>
+   <span>&#x531;.&#x53B;</span>
+   <span>&#x531;.&#x53C;</span>
+   <span>&#x531;.&#x53D;</span>
+   <span>&#x531;.&#x53E;</span>
+   <span>&#x531;.&#x53F;</span>
+   <span>&#x531;.&#x540;</span>
+   <span>&#x531;.&#x541;</span>
+   <span>&#x531;.&#x542;</span>
+   <span>&#x531;.&#x543;</span>
+   <span>&#x531;.&#x544;</span>
+   <span>&#x531;.&#x545;</span>
+   <span>&#x531;.&#x546;</span>
+   <span>&#x531;.&#x547;</span>
+   <span>&#x531;.&#x548;</span>
+   <span>&#x531;.&#x549;</span>
+   <span>&#x531;.&#x54A;</span>
+   <span>&#x531;.&#x54B;</span>
+   <span>&#x531;.&#x54C;</span>
+   <span>&#x531;.&#x54D;</span>
+   <span>&#x531;.&#x54E;</span>
+   <span>&#x531;.&#x54F;</span>
+   <span>&#x531;.&#x550;</span>
+   <span>&#x531;.&#x551;</span>
+   <span>&#x531;.&#x552;</span>
+   <span>&#x531;.&#x553;</span>
+   <span>&#x531;.&#x554;</span>
+   <span>&#x531;.&#x554;&#x54B;&#x542;&#x539;</span>
  </div>
 
  </body>
diff --git a/layout/reftests/counters/t1204-reset-00-c-o-reference.html b/layout/reftests/counters/t1204-reset-00-c-o-reference.html
index 3be209b7e8..e9afee0b67 100644
--- a/layout/reftests/counters/t1204-reset-00-c-o-reference.html
+++ b/layout/reftests/counters/t1204-reset-00-c-o-reference.html
@@ -9,7 +9,7 @@
  </head>
  <body>
 
- <div id="reference"><span>1-</span><span>2-</span><span>3-</span></div>
+ <div id="reference"><span>1-</span><span>1.1-</span><span>1.2-</span></div>
 
  </body>
 </html>
diff --git a/layout/reftests/counters/t120401-scope-01-c-reference.html b/layout/reftests/counters/t120401-scope-01-c-reference.html
index 021366aaed..c7488ce4b3 100644
--- a/layout/reftests/counters/t120401-scope-01-c-reference.html
+++ b/layout/reftests/counters/t120401-scope-01-c-reference.html
@@ -10,7 +10,7 @@
  <body>
 
 
- <div><span>B</span><span>1</span><span>-</span><span>B</span><span>2</span><span>-</span><span>B</span><span>2.1</span><span>-</span><span>B</span><span>2.2</span><span>-</span><span>A</span><span>2.3</span><span>-</span><span>B</span><span>2.4</span><span>-</span><span>A</span><span>2.5</span><span>-</span><span>A</span><span>2.6</span><span>-</span><span>B</span><span>3</span><span>-</span><span>B</span><span>4</span><span>-</span><span>A</span><span>5</span><span>-</span><span>A</span><span>6</span><span>-</span><span>A</span><span>7</span><span>-</span><span>A</span><span>8</span><span>-</span></div>
+ <div><span>B</span><span>1</span><span>-</span><span>B</span><span>2</span><span>-</span><span>B</span><span>2.1</span><span>-</span><span>B</span><span>2.2</span><span>-</span><span>A</span><span>2.3</span><span>-</span><span>B</span><span>2.4</span><span>-</span><span>A</span><span>2.5</span><span>-</span><span>A</span><span>2.6</span><span>-</span><span>B</span><span>2.7</span><span>-</span><span>B</span><span>2.8</span><span>-</span><span>A</span><span>2.9</span><span>-</span><span>A</span><span>2.10</span><span>-</span><span>A</span><span>2.11</span><span>-</span><span>A</span><span>3</span><span>-</span></div>
 
  </body>
 </html>
diff --git a/layout/reftests/counters/t120401-scope-02-c-reference.html b/layout/reftests/counters/t120401-scope-02-c-reference.html
index 41fc79875a..ff2281a8cf 100644
--- a/layout/reftests/counters/t120401-scope-02-c-reference.html
+++ b/layout/reftests/counters/t120401-scope-02-c-reference.html
@@ -10,7 +10,7 @@
  <body>
 
 
- <div><span>B</span><span>1</span><span>-</span><span>B</span><span>1.1</span><span>-</span><span>B</span><span>2</span><span>-</span><span>A</span><span>3</span><span>-</span><span>A</span><span>4</span><span>-</span><span>A</span><span>5</span><span>-</span></div>
+ <div><span>B</span><span>1</span><span>-</span><span>B</span><span>1.1</span><span>-</span><span>B</span><span>1.2</span><span>-</span><span>A</span><span>1.3</span><span>-</span><span>A</span><span>1.4</span><span>-</span><span>A</span><span>2</span><span>-</span></div>
 
  </body>
 </html>
diff --git a/layout/reftests/dom/reftest.list b/layout/reftests/dom/reftest.list
index 64ac914010..897af84d11 100644
--- a/layout/reftests/dom/reftest.list
+++ b/layout/reftests/dom/reftest.list
@@ -28,7 +28,7 @@
 # a range insert and an append
 == insertmultiplemultiple-2.html insertmultiplemultiple-ref.html
 # multiple range inserts and an append
-== insertmultiplemultiple-2.html insertmultiplemultiple-ref.html
+== insertmultiplemultiple-3.html insertmultiplemultiple-ref.html
 
 # testing bindings that have multiple insertion points
 == multipleinsertionpoints-ref2-shadow.xhtml multipleinsertionpoints-ref.xhtml
diff --git a/layout/reftests/flexbox/reftest.list b/layout/reftests/flexbox/reftest.list
index dbd6c705cd..b96dbf4fce 100644
--- a/layout/reftests/flexbox/reftest.list
+++ b/layout/reftests/flexbox/reftest.list
@@ -75,7 +75,6 @@ fuzzy(0-3,0-10) == flexbox-dyn-insertAroundSpan-3.xhtml flexbox-dyn-insertAround
 == flexbox-position-absolute-2.xhtml  flexbox-position-absolute-2-ref.xhtml
 == flexbox-position-absolute-3.xhtml  flexbox-position-absolute-3-ref.xhtml
 == flexbox-position-absolute-4.xhtml  flexbox-position-absolute-4-ref.xhtml
-== flexbox-position-fixed-3.xhtml     flexbox-position-fixed-3-ref.xhtml
 fuzzy-if(Android,0-16,0-400) == flexbox-position-fixed-1.xhtml     flexbox-position-fixed-1-ref.xhtml
 fuzzy-if(Android,0-16,0-400) == flexbox-position-fixed-2.xhtml     flexbox-position-fixed-2-ref.xhtml
 == flexbox-position-fixed-3.xhtml     flexbox-position-fixed-3-ref.xhtml
diff --git a/layout/reftests/forms/input/range/1887539-ref.html b/layout/reftests/forms/input/range/1887539-ref.html
new file mode 100644
index 0000000000..b539a1b5c2
--- /dev/null
+++ b/layout/reftests/forms/input/range/1887539-ref.html
@@ -0,0 +1,30 @@
+<!doctype html>
+<style>
+#scrubber {
+  height: 100px;
+  width: 100%;
+  appearance: none;
+  background-color: black;
+  box-sizing: border-box;
+  padding: 6px 2px;
+  margin: 0;
+
+  &::-moz-range-thumb {
+    border-radius: 14px;
+    background-color: #BFBFC9;
+    width: 8px;
+    height: 8px;
+    border: 3px solid white;
+    padding: 0;
+  }
+
+  &::-moz-range-track {
+    background-color: #969696;
+  }
+
+  &::-moz-range-progress {
+    background-color: white;
+  }
+}
+</style>
+<input type="range" id="scrubber" value="0.5" min="0" max="1" step=".001">
diff --git a/layout/reftests/forms/input/range/1887539.html b/layout/reftests/forms/input/range/1887539.html
new file mode 100644
index 0000000000..9472af203e
--- /dev/null
+++ b/layout/reftests/forms/input/range/1887539.html
@@ -0,0 +1,35 @@
+<!doctype html>
+<style>
+#scrubber {
+  height: 100px;
+  width: 100%;
+  appearance: none;
+  background-color: black;
+  box-sizing: border-box;
+  padding: 6px 2px;
+  margin: 0;
+
+  &::-moz-range-thumb {
+    border-radius: 14px;
+    background-color: #BFBFC9;
+    width: 8px;
+    height: 8px;
+    border: 3px solid white;
+    padding: 0;
+  }
+
+  &::-moz-range-track {
+    background-color: #969696;
+  }
+
+  &::-moz-range-progress {
+    background-color: white;
+  }
+}
+</style>
+<input type="range" id="scrubber" value="0" min="0" max="1" step=".001">
+<script>
+let scrubber = document.getElementById('scrubber');
+scrubber.getBoundingClientRect();
+scrubber.value = 0.5;
+</script>
diff --git a/layout/reftests/forms/input/range/reftest.list b/layout/reftests/forms/input/range/reftest.list
index 181097dc15..f98f345b95 100644
--- a/layout/reftests/forms/input/range/reftest.list
+++ b/layout/reftests/forms/input/range/reftest.list
@@ -59,3 +59,5 @@ skip-if(Android) == range-border-background.html range-border-background-ref.htm
 fails-if(Android) fuzzy(0-2,0-80) == auto-size.html auto-size-ref.html # Snapping, bug 1621141
 == range-track-bg.html range-track-bg-ref.html
 != track-default-rendering.html track-default-rendering-ref.html
+
+== 1887539.html 1887539-ref.html
diff --git a/layout/reftests/marquee/336736-1a-ref.html b/layout/reftests/marquee/336736-1a-ref.html
new file mode 100644
index 0000000000..690992b8a5
--- /dev/null
+++ b/layout/reftests/marquee/336736-1a-ref.html
@@ -0,0 +1,5 @@
+<html>
+<body dir="rtl">
+<div style="background: green; width: 50px">&nbsp;</div>
+</body>
+</html>
diff --git a/layout/reftests/marquee/336736-1-ref.html b/layout/reftests/marquee/336736-1b-ref.html
index 116e5ade28..116e5ade28 100644
--- a/layout/reftests/marquee/336736-1-ref.html
+++ b/layout/reftests/marquee/336736-1b-ref.html
diff --git a/layout/reftests/marquee/reftest.list b/layout/reftests/marquee/reftest.list
index ac6772f6c9..c7d2fafd30 100644
--- a/layout/reftests/marquee/reftest.list
+++ b/layout/reftests/marquee/reftest.list
@@ -1,6 +1,6 @@
 == 166591-dynamic-1.html 166591-dynamic-1-ref.html
-fuzzy-if(Android,0-8,0-50) == 336736-1a.html 336736-1-ref.html
-fuzzy-if(Android,0-8,0-50) == 336736-1b.html 336736-1-ref.html
+fuzzy-if(Android,0-8,0-50) == 336736-1a.html 336736-1a-ref.html
+fuzzy-if(Android,0-8,0-50) == 336736-1b.html 336736-1b-ref.html
 == 406073-1.html 406073-1-ref.html
 == 407016-2.html 407016-2-ref.html
 fuzzy-if(Android,0-8,0-220) == 413027-4.html 413027-4-ref.html
diff --git a/layout/reftests/moz.build b/layout/reftests/moz.build
index 14b30d92a3..261ea6db09 100644
--- a/layout/reftests/moz.build
+++ b/layout/reftests/moz.build
@@ -171,8 +171,6 @@ with Files("native-theme/**"):
     BUG_COMPONENT = ("Core", "Layout")
 with Files("object/**"):
     BUG_COMPONENT = ("Core", "DOM: Core & HTML")
-with Files("ogg-video/**"):
-    BUG_COMPONENT = ("Core", "Audio/Video")
 with Files("outline/**"):
     BUG_COMPONENT = ("Core", "Layout")
 with Files("pagination/**"):
diff --git a/layout/reftests/ogg-video/444-1-ref.html b/layout/reftests/ogg-video/444-1-ref.html
deleted file mode 100644
index 08e4df28ee..0000000000
--- a/layout/reftests/ogg-video/444-1-ref.html
+++ /dev/null
@@ -1,20 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body>
-<video id="v1" style="position:absolute; left:0; top:0"></video>
-<!-- hide bottom of video -->
-<div style="position:absolute; top:120px; left:0; right:0; bottom:0; background:black"></div>
-<script>
-function doTest() {
-  // Set source now so that the loadeddata event can't fire before
-  // this function runs.
-  v1.src = "seek420.ogv";
-  v1.play();
-  v1.addEventListener("loadeddata", function() {
-    setTimeout(function() {
-      document.documentElement.removeAttribute('class');
-    }, 50);
-  });
-}
-document.addEventListener("MozReftestInvalidate", doTest);
-</script>
diff --git a/layout/reftests/ogg-video/444-1.html b/layout/reftests/ogg-video/444-1.html
deleted file mode 100644
index 02e7b3ddb8..0000000000
--- a/layout/reftests/ogg-video/444-1.html
+++ /dev/null
@@ -1,20 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body>
-<video id="v1" style="position:absolute; left:0; top:0"></video>
-<!-- hide bottom of video -->
-<div style="position:absolute; top:120px; left:0; right:0; bottom:0; background:black"></div>
-<script>
-function doTest() {
-  // Set source now so that the loadeddata event can't fire before
-  // this function runs.
-  v1.src = "seek444.ogv";
-  v1.play();
-  v1.addEventListener("loadeddata", function() {
-    setTimeout(function() {
-      document.documentElement.removeAttribute('class');
-    }, 50);
-  });
-}
-document.addEventListener("MozReftestInvalidate", doTest);
-</script>
diff --git a/layout/reftests/ogg-video/aspect-ratio-1-ref.html b/layout/reftests/ogg-video/aspect-ratio-1-ref.html
deleted file mode 100644
index 93391ed83c..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-1-ref.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<div style="width:140px; height:100px; position:relative; left:100px; top:100px; background:black;"></div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/aspect-ratio-1a.xhtml b/layout/reftests/ogg-video/aspect-ratio-1a.xhtml
deleted file mode 100644
index c70d3248f5..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-1a.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" style="width:340px; height:100px; position:relative; top:100px;"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/aspect-ratio-1b.xhtml b/layout/reftests/ogg-video/aspect-ratio-1b.xhtml
deleted file mode 100644
index b59352b516..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-1b.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" style="width:140px; height:300px; position:relative; left:100px;"></video>
-</body>
-</html>
-</foreignObject>
-</svg>  
diff --git a/layout/reftests/ogg-video/aspect-ratio-2-ref.html b/layout/reftests/ogg-video/aspect-ratio-2-ref.html
deleted file mode 100644
index 4f78ab4d2f..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-2-ref.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<div style="width:280px; height:200px; position:relative; left:200px; top:200px; background:black;"></div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/aspect-ratio-2a.xhtml b/layout/reftests/ogg-video/aspect-ratio-2a.xhtml
deleted file mode 100644
index f708ec90af..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-2a.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" style="width:680px; height:200px; position:relative; top:200px;"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/aspect-ratio-2b.xhtml b/layout/reftests/ogg-video/aspect-ratio-2b.xhtml
deleted file mode 100644
index e7469031a8..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-2b.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" style="width:280px; height:600px; position:relative; left:200px;"></video>
-</body>
-</html>
-</foreignObject>
-</svg>  
diff --git a/layout/reftests/ogg-video/aspect-ratio-3-ref.xhtml b/layout/reftests/ogg-video/aspect-ratio-3-ref.xhtml
deleted file mode 100644
index 73662654f8..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-3-ref.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" style="width:280px; height:200px;"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/aspect-ratio-3a.xhtml b/layout/reftests/ogg-video/aspect-ratio-3a.xhtml
deleted file mode 100644
index 3c253e8f81..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-3a.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" width="280"></video>
-</body>
-</html>
-</foreignObject>
-</svg>  
diff --git a/layout/reftests/ogg-video/aspect-ratio-3b.xhtml b/layout/reftests/ogg-video/aspect-ratio-3b.xhtml
deleted file mode 100644
index cc6ec4c750..0000000000
--- a/layout/reftests/ogg-video/aspect-ratio-3b.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv" height="200"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/basic-1-ref.html b/layout/reftests/ogg-video/basic-1-ref.html
deleted file mode 100644
index aca3dcb9ca..0000000000
--- a/layout/reftests/ogg-video/basic-1-ref.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<div style="width:140px; height:100px; background:black;"></div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/basic-1.xhtml b/layout/reftests/ogg-video/basic-1.xhtml
deleted file mode 100644
index 4899dc29f7..0000000000
--- a/layout/reftests/ogg-video/basic-1.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black140x100.ogv"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/black100x100-aspect3to2.ogv b/layout/reftests/ogg-video/black100x100-aspect3to2.ogv
deleted file mode 100644
index 81fe51ffb3..0000000000
--- a/layout/reftests/ogg-video/black100x100-aspect3to2.ogv
+++ /dev/null
diff --git a/layout/reftests/ogg-video/black140x100.ogv b/layout/reftests/ogg-video/black140x100.ogv
deleted file mode 100644
index ab146ebe28..0000000000
--- a/layout/reftests/ogg-video/black140x100.ogv
+++ /dev/null
diff --git a/layout/reftests/ogg-video/black29x19offset.ogv b/layout/reftests/ogg-video/black29x19offset.ogv
deleted file mode 100644
index b515ebd1f3..0000000000
--- a/layout/reftests/ogg-video/black29x19offset.ogv
+++ /dev/null
diff --git a/layout/reftests/ogg-video/blue140x100.png b/layout/reftests/ogg-video/blue140x100.png
deleted file mode 100644
index f4c3973fcc..0000000000
--- a/layout/reftests/ogg-video/blue140x100.png
+++ /dev/null
diff --git a/layout/reftests/ogg-video/blue250x200.png b/layout/reftests/ogg-video/blue250x200.png
deleted file mode 100644
index 5eb0b52511..0000000000
--- a/layout/reftests/ogg-video/blue250x200.png
+++ /dev/null
diff --git a/layout/reftests/ogg-video/canvas-1a.xhtml b/layout/reftests/ogg-video/canvas-1a.xhtml
deleted file mode 100644
index 9f115e785f..0000000000
--- a/layout/reftests/ogg-video/canvas-1a.xhtml
+++ /dev/null
@@ -1,29 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1" class="reftest-wait">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body>
-<canvas id="canvas" width="200" height="200"></canvas>
-<script>
-var video = document.createElement("video");
-video.src = "black140x100.ogv";
-video.load();
-function draw() {
-  var canvas = document.getElementById("canvas");
-  var ctx = canvas.getContext("2d");
-  try {
-    ctx.drawImage(video, 0, 0, video.videoWidth, video.videoHeight);
-  } catch (e) {
-  }
-  document.documentElement.removeAttribute("class");
-}
-video.addEventListener("loadeddata", draw, false);
-</script>
-</body>
-</html>
-</foreignObject>
-</svg>  
diff --git a/layout/reftests/ogg-video/canvas-1b.xhtml b/layout/reftests/ogg-video/canvas-1b.xhtml
deleted file mode 100644
index 4524593e9e..0000000000
--- a/layout/reftests/ogg-video/canvas-1b.xhtml
+++ /dev/null
@@ -1,27 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body>
-<canvas id="canvas" width="200" height="200"></canvas>
-<script>
-function draw() {
-  var video = document.getElementById("video");
-  var canvas = document.getElementById("canvas");
-  var ctx = canvas.getContext("2d");
-  try {
-    ctx.drawImage(video, 0, 0, video.videoWidth, video.videoHeight);
-  } catch (e) {
-  }
-  document.documentElement.removeAttribute("class");
-}
-</script>
-<video id="video" src="black140x100.ogv" onloadeddata="draw()" style="opacity:0"></video>
-</body>
-</html>
-</foreignObject>
-</svg>  
diff --git a/layout/reftests/ogg-video/clipping-1-ref.html b/layout/reftests/ogg-video/clipping-1-ref.html
deleted file mode 100644
index 67782811c5..0000000000
--- a/layout/reftests/ogg-video/clipping-1-ref.html
+++ /dev/null
@@ -1,9 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white">
-<div style="position:absolute; left:0; top:0; width:200px; height:600px;">
-  <video src="black140x100.ogv" style="width:400px; margin-left:-100px;"></video>
-</div>
-<div style="position:absolute; left:200px; top:0; background:white; width:200px; height:600px;"></div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/clipping-1a.html b/layout/reftests/ogg-video/clipping-1a.html
deleted file mode 100644
index cfae72cedd..0000000000
--- a/layout/reftests/ogg-video/clipping-1a.html
+++ /dev/null
@@ -1,8 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white">
-<div style="overflow:hidden; position:absolute; left:0; top:0; width:200px; height:600px;">
-  <video src="black140x100.ogv" style="width:400px; margin-left:-100px;"></video>
-</div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/empty-1-ref.html b/layout/reftests/ogg-video/empty-1-ref.html
deleted file mode 100644
index fcc7693202..0000000000
--- a/layout/reftests/ogg-video/empty-1-ref.html
+++ /dev/null
@@ -1,5 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/empty-1a.html b/layout/reftests/ogg-video/empty-1a.html
deleted file mode 100644
index fc1421a810..0000000000
--- a/layout/reftests/ogg-video/empty-1a.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<video src="black140x100.ogv" style="width:0"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/empty-1b.html b/layout/reftests/ogg-video/empty-1b.html
deleted file mode 100644
index 9dd17dbbaa..0000000000
--- a/layout/reftests/ogg-video/empty-1b.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<video src="black140x100.ogv" style="height:0"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/encoded-aspect-ratio-1-ref.html b/layout/reftests/ogg-video/encoded-aspect-ratio-1-ref.html
deleted file mode 100644
index d9c0054eb5..0000000000
--- a/layout/reftests/ogg-video/encoded-aspect-ratio-1-ref.html
+++ /dev/null
@@ -1,19 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<div style="background-color: black; width: 150px; height: 100px; position: absolute; left: 10px; top: 10px;"></div>
-
-<!-- Left side vertical. -->
-<div style="position: absolute; left: 9px; top: 9px; width: 2px; height: 102px; z-index: 2; background: red;"></div>
-
-<!-- Right side vertical. -->
-<div style="position: absolute; left: 159px; top: 9px; width: 2px; height: 102px; z-index: 2; background: red;"></div>
-
-<!-- Top horizontal bar. -->
-<div style="position: absolute; left: 9px; top: 9px; width: 152px; height: 2px; z-index: 2; background: red;"></div>
-
-<!-- Bottom horizontal bar. -->
-<div style="position: absolute; left: 9px; top: 109px; width: 152px; height: 2px; z-index: 2; background: red;"></div>
-
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/encoded-aspect-ratio-1.html b/layout/reftests/ogg-video/encoded-aspect-ratio-1.html
deleted file mode 100644
index 238fdbfe8d..0000000000
--- a/layout/reftests/ogg-video/encoded-aspect-ratio-1.html
+++ /dev/null
@@ -1,29 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<!--
-     Test if video displays correctly with a 3:2 aspect ratio.
-     It should display at w=150 h=100.
-     On some Linux systems, the scaling to preserve the aspect ratio can sample
-     the pixels outside visible region. This results in a thin grey line down
-     some sides of the scaled picture. We add red bars over the edges to
-     overwrite such happenings, to make the test reliable.
--->
-<video src="black100x100-aspect3to2.ogv"
-       style="position:absolute; left: 10px; top: 10px; z-index: 1;">
-</video>
-
-<!-- Left side vertical. -->
-<div style="position: absolute; left: 9px; top: 9px; width: 2px; height: 102px; z-index: 2; background: red;"></div>
-
-<!-- Right side vertical. -->
-<div style="position: absolute; left: 159px; top: 9px; width: 2px; height: 102px; z-index: 2; background: red;"></div>
-
-<!-- Top horizontal bar. -->
-<div style="position: absolute; left: 9px; top: 9px; width: 152px; height: 2px; z-index: 2; background: red;"></div>
-
-<!-- Bottom horizontal bar. -->
-<div style="position: absolute; left: 9px; top: 109px; width: 152px; height: 2px; z-index: 2; background: red;"></div>
-
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/green70x30.png b/layout/reftests/ogg-video/green70x30.png
deleted file mode 100644
index b2bf32762d..0000000000
--- a/layout/reftests/ogg-video/green70x30.png
+++ /dev/null
diff --git a/layout/reftests/ogg-video/object-aspect-ratio-1a.xhtml b/layout/reftests/ogg-video/object-aspect-ratio-1a.xhtml
deleted file mode 100644
index 29fd619fd7..0000000000
--- a/layout/reftests/ogg-video/object-aspect-ratio-1a.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<object data="black140x100.ogv" style="width:340px; height:100px; position:relative; top:100px;"></object>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/object-aspect-ratio-1b.xhtml b/layout/reftests/ogg-video/object-aspect-ratio-1b.xhtml
deleted file mode 100644
index ea1f02ff74..0000000000
--- a/layout/reftests/ogg-video/object-aspect-ratio-1b.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<object data="black140x100.ogv" style="width:140px; height:300px; position:relative; left:100px;"></object>
-</body>
-</html>
-</foreignObject>
-</svg>  
diff --git a/layout/reftests/ogg-video/object-aspect-ratio-2a.xhtml b/layout/reftests/ogg-video/object-aspect-ratio-2a.xhtml
deleted file mode 100644
index 36b4cc0c1e..0000000000
--- a/layout/reftests/ogg-video/object-aspect-ratio-2a.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<object data="black140x100.ogv" style="width:680px; height:200px; position:relative; top:200px;"></object>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/object-aspect-ratio-2b.xhtml b/layout/reftests/ogg-video/object-aspect-ratio-2b.xhtml
deleted file mode 100644
index d557921d2f..0000000000
--- a/layout/reftests/ogg-video/object-aspect-ratio-2b.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<object data="black140x100.ogv" style="width:280px; height:600px; position:relative; left:200px;"></object>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/offset-1-ref.html b/layout/reftests/ogg-video/offset-1-ref.html
deleted file mode 100644
index 61a1dc83a7..0000000000
--- a/layout/reftests/ogg-video/offset-1-ref.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<div style="width:29px; height:29px; background:black;"></div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/offset-1.xhtml b/layout/reftests/ogg-video/offset-1.xhtml
deleted file mode 100644
index 3504734907..0000000000
--- a/layout/reftests/ogg-video/offset-1.xhtml
+++ /dev/null
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject filter="url(../filters.svg#ThresholdRGB)" x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white;">
-<video src="black29x19offset.ogv"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/ogg-video/poster-1.html b/layout/reftests/ogg-video/poster-1.html
deleted file mode 100644
index 15e3cb5462..0000000000
--- a/layout/reftests/ogg-video/poster-1.html
+++ /dev/null
@@ -1,7 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<!-- Ensure video element displays at poster size when video's intrinsic size isn't available. -->
-<video preload="none" src="black140x100.ogv" poster="blue250x200.png"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-10.html b/layout/reftests/ogg-video/poster-10.html
deleted file mode 100644
index 546b96a46f..0000000000
--- a/layout/reftests/ogg-video/poster-10.html
+++ /dev/null
@@ -1,18 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<!-- Test: Create video, add poster, load. Should display poster. -->
-<script>
-function runTest() {
-  var v = document.createElement('video');
-  v.addEventListener('loadeddata', function(){setTimeout(function(){document.documentElement.className = '';}, 0);});
-  v.id = 'v';
-  v.src = "black140x100.ogv";
-  v.poster = "blue250x200.png";
-  v.preload = "auto";
-  document.body.appendChild(v);
-}
-
-</script>
-<body style="background:white;" onload="runTest();">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-11.html b/layout/reftests/ogg-video/poster-11.html
deleted file mode 100644
index a2f186a4bb..0000000000
--- a/layout/reftests/ogg-video/poster-11.html
+++ /dev/null
@@ -1,29 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<!-- Test: Create video, load. Add poster frame, load again, poster should show. -->
-<script>
-function runTest() {
-  var v = document.createElement('video');
-  
-  var endTest = function() {
-    setTimeout(function(){document.documentElement.className = '';}, 0);
-  };  
-  
-  var addPoster = function() {
-    v.removeEventListener('loadeddata', addPoster);
-    v.poster = "blue140x100.png";
-    v.addEventListener('loadeddata', endTest);
-    v.load();
-  };
-  
-  v.addEventListener('loadeddata', addPoster);
-  v.id = 'v';
-  v.src = "black140x100.ogv";
-  v.preload = "auto";
-  document.body.appendChild(v);
-}
-
-</script>
-<body style="background:white;" onload="runTest();">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-12.html b/layout/reftests/ogg-video/poster-12.html
deleted file mode 100644
index 49b6dbfebf..0000000000
--- a/layout/reftests/ogg-video/poster-12.html
+++ /dev/null
@@ -1,38 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<!-- Test: Create video, load, play. Add poster frame, load again, poster should show. -->
-<script>
-function runTest() {
-  var v = document.createElement('video');
-  
-  var endTest = function() {
-    setTimeout(function(){document.documentElement.className = '';}, 0);
-  };
-  
-  var play = 
-    function() {
-      v.removeEventListener('loadeddata', play);
-      v.play();
-    }
-
-  var addPoster = function() {
-    v.removeEventListener('playing', addPoster);
-    v.poster = "blue140x100.png";
-    v.addEventListener('loadeddata', endTest);
-    v.load();
-  };
-
-  v.addEventListener('loadeddata',
-                     play);
-  v.addEventListener('playing',
-                     addPoster);
-  v.id = 'v';
-  v.src = "black140x100.ogv";
-  v.preload = "auto";
-  document.body.appendChild(v);
-}
-
-</script>
-<body style="background:white;" onload="runTest();">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-13.html b/layout/reftests/ogg-video/poster-13.html
deleted file mode 100644
index 79c3b8c582..0000000000
--- a/layout/reftests/ogg-video/poster-13.html
+++ /dev/null
@@ -1,8 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<!-- Test that poster is resized, maintaining its aspect ratio. -->
-<video src="black140x100.ogv" poster="blue250x200.png" style="width: 288px; height: 216px;"></video>
-
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-15.html b/layout/reftests/ogg-video/poster-15.html
deleted file mode 100644
index 01c25b660e..0000000000
--- a/layout/reftests/ogg-video/poster-15.html
+++ /dev/null
@@ -1,13 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!-- Test that poster is correctly laid out inside borders. Also test that 
-     poster frames smaller than video don't have the video frame drawn behind
-     them etc. -->
-<body style="background:white;">
-<video src="black140x100.ogv"
-       poster="green70x30.png"
-       preload="none"
-       style="border: solid blue 2px;">
-</video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-2.html b/layout/reftests/ogg-video/poster-2.html
deleted file mode 100644
index 28b38f398c..0000000000
--- a/layout/reftests/ogg-video/poster-2.html
+++ /dev/null
@@ -1,7 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<!-- Test if poster frame with invalid poster displays video frame. -->
-<video src="black140x100.ogv" poster="not-a-valid-file"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-3.html b/layout/reftests/ogg-video/poster-3.html
deleted file mode 100644
index ae12c1b65d..0000000000
--- a/layout/reftests/ogg-video/poster-3.html
+++ /dev/null
@@ -1,11 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body style="background:white;">
-<!-- Test if poster hides after playing with autoplay. -->
-<video src="black140x100.ogv"
-       poster="blue250x200.png"
-       preload="auto"
-       autoplay
-       onplaying="setTimeout(function(){document.documentElement.className = '';},0);"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-4.html b/layout/reftests/ogg-video/poster-4.html
deleted file mode 100644
index 85453638c8..0000000000
--- a/layout/reftests/ogg-video/poster-4.html
+++ /dev/null
@@ -1,14 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body style="background:white;"
-      onload="setTimeout(function(){document.documentElement.className = '';}, 0);">
-<!-- Test if we show video frame after removing valid poster. -->
-<video src="black140x100.ogv"
-       preload="auto"
-       id="v"
-       poster="blue250x200.png"></video>
-<script type="text/javascript">
-  document.getElementById('v').poster = '';
-</script>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-5.html b/layout/reftests/ogg-video/poster-5.html
deleted file mode 100644
index 94049c92d7..0000000000
--- a/layout/reftests/ogg-video/poster-5.html
+++ /dev/null
@@ -1,13 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body style="background:white;">
-<!-- Test to ensure that changing the poster after video has painted its first
-     frame doesn't render the poster. The video frame should not change to the
-     poster, since it's already painted its first video frame. -->
-<video src="black140x100.ogv"
-       preload="auto"
-       id="v"
-       autoplay
-       onended="document.getElementById('v').poster = 'blue250x200.png'; setTimeout(function(){document.documentElement.className = '';},0);"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-6.html b/layout/reftests/ogg-video/poster-6.html
deleted file mode 100644
index c9ae5b88f5..0000000000
--- a/layout/reftests/ogg-video/poster-6.html
+++ /dev/null
@@ -1,12 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body style="background:white;">
-<!-- Test that poster frame should hide after completing a seek. -->
-<video src="black140x100.ogv"
-       preload="auto"
-       id="v"
-       onloadeddata="var v = document.getElementById('v'); v.currentTime = v.duration;"
-       onseeked="setTimeout(function(){document.documentElement.className = '';}, 0);"
-       poster="blue250x200.png"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-7.html b/layout/reftests/ogg-video/poster-7.html
deleted file mode 100644
index 4c3e002d37..0000000000
--- a/layout/reftests/ogg-video/poster-7.html
+++ /dev/null
@@ -1,14 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body style="background:white;"
-      onload="setTimeout(function(){document.documentElement.className = '';}, 0);">
-<!-- Test that poster frame changes when you change the poster attribute. -->
-<video src="black140x100.ogv"
-       preload="none"
-       id="v"
-       poster="blue250x200.png"></video>
-<script type="text/javascript">
-  document.getElementById('v').poster = 'red140x100.png';
-</script>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-8.html b/layout/reftests/ogg-video/poster-8.html
deleted file mode 100644
index c9e1fa37a0..0000000000
--- a/layout/reftests/ogg-video/poster-8.html
+++ /dev/null
@@ -1,12 +0,0 @@
-<!DOCTYPE HTML>
-<html class="reftest-wait">
-<body style="background:white;">
-<!-- Test if poster hides after playing with play() call. -->
-<video src="black140x100.ogv"
-       poster="blue250x200.png"
-       id="v"
-       preload="auto"
-       onloadeddata="document.getElementById('v').play();"
-       onplaying="setTimeout(function(){document.documentElement.className = '';}, 0);"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-ref-black140x100.html b/layout/reftests/ogg-video/poster-ref-black140x100.html
deleted file mode 100644
index 98f1a4cba7..0000000000
--- a/layout/reftests/ogg-video/poster-ref-black140x100.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<video src="black140x100.ogv" preload="auto"></video>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-ref-blue125x100.html b/layout/reftests/ogg-video/poster-ref-blue125x100.html
deleted file mode 100644
index 90795ae911..0000000000
--- a/layout/reftests/ogg-video/poster-ref-blue125x100.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<img src="blue140x100.png" alt="poster" style="position: absolute; height: 100px; width: 125px; left: 16px">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-ref-blue140x100.html b/layout/reftests/ogg-video/poster-ref-blue140x100.html
deleted file mode 100644
index 66540b8e85..0000000000
--- a/layout/reftests/ogg-video/poster-ref-blue140x100.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<img src="blue140x100.png" alt="poster">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-ref-blue250x200.html b/layout/reftests/ogg-video/poster-ref-blue250x200.html
deleted file mode 100644
index 050d53dfb3..0000000000
--- a/layout/reftests/ogg-video/poster-ref-blue250x200.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<img src="blue250x200.png" alt="poster">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-ref-blue400x300.html b/layout/reftests/ogg-video/poster-ref-blue400x300.html
deleted file mode 100644
index 8c32ff715d..0000000000
--- a/layout/reftests/ogg-video/poster-ref-blue400x300.html
+++ /dev/null
@@ -1,8 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<img src="blue250x200.png" style="position: relative; width: 270px; height: 216px; left: 9px;">
-</body>
-</html>
-
-
diff --git a/layout/reftests/ogg-video/poster-ref-green70x30.html b/layout/reftests/ogg-video/poster-ref-green70x30.html
deleted file mode 100644
index f979220a6a..0000000000
--- a/layout/reftests/ogg-video/poster-ref-green70x30.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<img src="green70x30.png" alt="poster" style="border: solid blue 2px;">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/poster-ref-red140x100.html b/layout/reftests/ogg-video/poster-ref-red140x100.html
deleted file mode 100644
index 3ac08d29e2..0000000000
--- a/layout/reftests/ogg-video/poster-ref-red140x100.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white;">
-<img src="red140x100.png" alt="poster">
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/red140x100.png b/layout/reftests/ogg-video/red140x100.png
deleted file mode 100644
index 20250771f3..0000000000
--- a/layout/reftests/ogg-video/red140x100.png
+++ /dev/null
diff --git a/layout/reftests/ogg-video/red160x120.png b/layout/reftests/ogg-video/red160x120.png
deleted file mode 100644
index 21737a0e8e..0000000000
--- a/layout/reftests/ogg-video/red160x120.png
+++ /dev/null
diff --git a/layout/reftests/ogg-video/reftest.list b/layout/reftests/ogg-video/reftest.list
deleted file mode 100644
index 2c9a96f8ee..0000000000
--- a/layout/reftests/ogg-video/reftest.list
+++ /dev/null
@@ -1,35 +0,0 @@
-# NOTE: bug 1084564 covers "fails"/"skip" annotations for android below:
-fuzzy(0-255,0-5000) == 444-1.html 444-1-ref.html
-fails-if(Android) == aspect-ratio-1a.xhtml aspect-ratio-1-ref.html
-fails-if(Android) == aspect-ratio-1b.xhtml aspect-ratio-1-ref.html
-fails-if(Android) skip-if(gtkWidget) == aspect-ratio-2a.xhtml aspect-ratio-2-ref.html
-fails-if(Android) skip-if(gtkWidget) == aspect-ratio-2b.xhtml aspect-ratio-2-ref.html
-== aspect-ratio-3a.xhtml aspect-ratio-3-ref.xhtml
-== aspect-ratio-3b.xhtml aspect-ratio-3-ref.xhtml
-fails-if(Android) random == encoded-aspect-ratio-1.html encoded-aspect-ratio-1-ref.html
-fails-if(Android) == basic-1.xhtml basic-1-ref.html
-== canvas-1a.xhtml basic-1-ref.html
-fails-if(Android) == canvas-1b.xhtml basic-1-ref.html
-== clipping-1a.html clipping-1-ref.html
-== empty-1a.html empty-1-ref.html
-== empty-1b.html empty-1-ref.html
-#these is skipped because we hang on the htmlparser tests when this is ran
-random == object-aspect-ratio-1a.xhtml aspect-ratio-1-ref.html
-random == object-aspect-ratio-1b.xhtml aspect-ratio-1-ref.html
-== offset-1.xhtml offset-1-ref.html
-random == object-aspect-ratio-2a.xhtml aspect-ratio-2-ref.html
-random == object-aspect-ratio-2b.xhtml aspect-ratio-2-ref.html
-fuzzy-if(winWidget,0-1,0-56000) fuzzy-if(cocoaWidget,0-1,0-56000) == zoomed-1.xhtml zoomed-1-ref.html # bug 778995 for fuzzy
-== poster-1.html poster-ref-blue250x200.html
-== poster-2.html poster-ref-black140x100.html
-== poster-3.html poster-ref-black140x100.html
-== poster-4.html poster-ref-black140x100.html
-== poster-5.html poster-ref-black140x100.html
-== poster-6.html poster-ref-black140x100.html
-== poster-7.html poster-ref-red140x100.html
-== poster-8.html poster-ref-black140x100.html
-random == poster-10.html poster-ref-blue125x100.html
-random == poster-11.html poster-ref-blue140x100.html
-random == poster-12.html poster-ref-blue140x100.html
-== poster-13.html poster-ref-blue400x300.html
-== poster-15.html poster-ref-green70x30.html
diff --git a/layout/reftests/ogg-video/seek420.ogv b/layout/reftests/ogg-video/seek420.ogv
deleted file mode 100644
index 2221cfef42..0000000000
--- a/layout/reftests/ogg-video/seek420.ogv
+++ /dev/null
diff --git a/layout/reftests/ogg-video/seek444.ogv b/layout/reftests/ogg-video/seek444.ogv
deleted file mode 100644
index a2453afeae..0000000000
--- a/layout/reftests/ogg-video/seek444.ogv
+++ /dev/null
diff --git a/layout/reftests/ogg-video/zoomed-1-ref.html b/layout/reftests/ogg-video/zoomed-1-ref.html
deleted file mode 100644
index 01929db7e7..0000000000
--- a/layout/reftests/ogg-video/zoomed-1-ref.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<body style="background:white; margin:0;">
-<div style="width:280px; height:200px; background:#010101;"></div>
-</body>
-</html>
diff --git a/layout/reftests/ogg-video/zoomed-1.xhtml b/layout/reftests/ogg-video/zoomed-1.xhtml
deleted file mode 100644
index e68e1290f4..0000000000
--- a/layout/reftests/ogg-video/zoomed-1.xhtml
+++ /dev/null
@@ -1,15 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg"
-     xmlns:xlink="http://www.w3.org/1999/xlink"
-     version="1.1" reftest-zoom="2"
-     width="50%" height="50%">
-<!-- use an empty g to force filters.svg to load before onload -->
-<use xlink:href="../filters.svg#empty" />
-<foreignObject x="0" y="0" height="100%" width="100%">
-<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
-<body style="background:white; margin:0">
-<video src="black140x100.ogv"></video>
-</body>
-</html>
-</foreignObject>
-</svg>
diff --git a/layout/reftests/reftest.list b/layout/reftests/reftest.list
index 9587c70798..97f04542ff 100644
--- a/layout/reftests/reftest.list
+++ b/layout/reftests/reftest.list
@@ -273,9 +273,6 @@ include outline/reftest.list
 # object/
 include object/reftest.list
 
-# ogg-video/
-skip include ogg-video/reftest.list
-
 # webm-video/
 skip include webm-video/reftest.list
 
diff --git a/layout/reftests/transform-3d/reftest.list b/layout/reftests/transform-3d/reftest.list
index affea05d0b..1f865ac3a7 100644
--- a/layout/reftests/transform-3d/reftest.list
+++ b/layout/reftests/transform-3d/reftest.list
@@ -10,7 +10,6 @@ fuzzy(0-1,0-6) == rotatey-1a.html rotatey-1-ref.html
 # perspective should only apply to child elements
 == rotatex-perspective-1c.html rotatex-1-ref.html
 == rotatex-perspective-3a.html rotatex-perspective-3-ref.html
-== scalez-1a.html scalez-1-ref.html
 fuzzy(0-16,0-346) fuzzy-if(cocoaWidget,0-200,0-310) fuzzy-if(winWidget,0-175,0-250) == preserve3d-1a.html preserve3d-1-ref.html
 == preserve3d-1b.html about:blank
 == preserve3d-clipped.html about:blank
diff --git a/layout/style/CSSPageRule.cpp b/layout/style/CSSPageRule.cpp
index 04d064b362..fb7dcbc38b 100644
--- a/layout/style/CSSPageRule.cpp
+++ b/layout/style/CSSPageRule.cpp
@@ -94,20 +94,20 @@ CSSPageRuleDeclaration::GetParsingEnvironment(
 CSSPageRule::CSSPageRule(RefPtr<StyleLockedPageRule> aRawRule,
                          StyleSheet* aSheet, css::Rule* aParentRule,
                          uint32_t aLine, uint32_t aColumn)
-    : css::Rule(aSheet, aParentRule, aLine, aColumn),
+    : css::GroupRule(aSheet, aParentRule, aLine, aColumn),
       mRawRule(std::move(aRawRule)),
       mDecls(Servo_PageRule_GetStyle(mRawRule).Consume()) {}
 
-NS_IMPL_ADDREF_INHERITED(CSSPageRule, css::Rule)
-NS_IMPL_RELEASE_INHERITED(CSSPageRule, css::Rule)
+NS_IMPL_ADDREF_INHERITED(CSSPageRule, css::GroupRule)
+NS_IMPL_RELEASE_INHERITED(CSSPageRule, css::GroupRule)
 
 // QueryInterface implementation for PageRule
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(CSSPageRule)
-NS_INTERFACE_MAP_END_INHERITING(css::Rule)
+NS_INTERFACE_MAP_END_INHERITING(css::GroupRule)
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(CSSPageRule)
 
-NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(CSSPageRule, css::Rule)
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(CSSPageRule, css::GroupRule)
   // Keep this in sync with IsCCLeaf.
 
   // Trace the wrapper for our declaration.  This just expands out
@@ -124,14 +124,14 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(CSSPageRule)
   // Note that this has to happen before unlinking css::Rule.
   tmp->UnlinkDeclarationWrapper(tmp->mDecls);
   tmp->mDecls.mDecls->SetOwningRule(nullptr);
-NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(css::Rule)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(css::GroupRule)
 
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(CSSPageRule, css::Rule)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(CSSPageRule, css::GroupRule)
   // Keep this in sync with IsCCLeaf.
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 bool CSSPageRule::IsCCLeaf() const {
-  if (!Rule::IsCCLeaf()) {
+  if (!GroupRule::IsCCLeaf()) {
     return false;
   }
 
@@ -147,7 +147,7 @@ StyleCssRuleType CSSPageRule::Type() const { return StyleCssRuleType::Page; }
 
 size_t CSSPageRule::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
   // TODO Implement this!
-  return aMallocSizeOf(this);
+  return GroupRule::SizeOfExcludingThis(aMallocSizeOf) + aMallocSizeOf(this);
 }
 
 #ifdef DEBUG
@@ -188,6 +188,10 @@ void CSSPageRule::SetSelectorText(const nsACString& aSelectorText) {
   }
 }
 
+already_AddRefed<StyleLockedCssRules> CSSPageRule::GetOrCreateRawRules() {
+  return Servo_PageRule_GetRules(mRawRule).Consume();
+}
+
 nsICSSDeclaration* CSSPageRule::Style() { return &mDecls; }
 
 JSObject* CSSPageRule::WrapObject(JSContext* aCx,
diff --git a/layout/style/CSSPageRule.h b/layout/style/CSSPageRule.h
index 705d526bdf..904f94d2c0 100644
--- a/layout/style/CSSPageRule.h
+++ b/layout/style/CSSPageRule.h
@@ -7,7 +7,7 @@
 #ifndef mozilla_dom_CSSPageRule_h
 #define mozilla_dom_CSSPageRule_h
 
-#include "mozilla/css/Rule.h"
+#include "mozilla/css/GroupRule.h"
 #include "mozilla/ServoBindingTypes.h"
 
 #include "nsDOMCSSDeclaration.h"
@@ -53,13 +53,14 @@ class CSSPageRuleDeclaration final : public nsDOMCSSDeclaration {
   RefPtr<DeclarationBlock> mDecls;
 };
 
-class CSSPageRule final : public css::Rule {
+class CSSPageRule final : public css::GroupRule {
  public:
   CSSPageRule(RefPtr<StyleLockedPageRule> aRawRule, StyleSheet* aSheet,
               css::Rule* aParentRule, uint32_t aLine, uint32_t aColumn);
 
   NS_DECL_ISUPPORTS_INHERITED
-  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(CSSPageRule, css::Rule)
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(CSSPageRule,
+                                                         css::GroupRule)
 
   bool IsCCLeaf() const final;
 
@@ -76,6 +77,8 @@ class CSSPageRule final : public css::Rule {
 
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const final;
 
+  already_AddRefed<StyleLockedCssRules> GetOrCreateRawRules() final;
+
 #ifdef DEBUG
   void List(FILE* out = stdout, int32_t aIndent = 0) const final;
 #endif
diff --git a/layout/style/CSSScopeRule.cpp b/layout/style/CSSScopeRule.cpp
new file mode 100644
index 0000000000..18047a582b
--- /dev/null
+++ b/layout/style/CSSScopeRule.cpp
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/CSSScopeRule.h"
+#include "mozilla/dom/CSSScopeRuleBinding.h"
+#include "mozilla/ServoBindings.h"
+
+namespace mozilla::dom {
+
+CSSScopeRule::CSSScopeRule(RefPtr<StyleScopeRule> aRawRule, StyleSheet* aSheet,
+                           css::Rule* aParentRule, uint32_t aLine,
+                           uint32_t aColumn)
+    : css::GroupRule(aSheet, aParentRule, aLine, aColumn),
+      mRawRule(std::move(aRawRule)) {}
+
+NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(CSSScopeRule, css::GroupRule)
+
+// QueryInterface implementation for SupportsRule
+
+#ifdef DEBUG
+void CSSScopeRule::List(FILE* out, int32_t aIndent) const {
+  nsAutoCString str;
+  for (int32_t i = 0; i < aIndent; i++) {
+    str.AppendLiteral("  ");
+  }
+  Servo_ScopeRule_Debug(mRawRule, &str);
+  fprintf_stderr(out, "%s\n", str.get());
+}
+#endif
+
+StyleCssRuleType CSSScopeRule::Type() const { return StyleCssRuleType::Scope; }
+
+already_AddRefed<StyleLockedCssRules> CSSScopeRule::GetOrCreateRawRules() {
+  return Servo_ScopeRule_GetRules(mRawRule).Consume();
+}
+
+void CSSScopeRule::SetRawAfterClone(RefPtr<StyleScopeRule> aRaw) {
+  mRawRule = std::move(aRaw);
+  css::GroupRule::DidSetRawAfterClone();
+}
+
+void CSSScopeRule::GetCssText(nsACString& aCssText) const {
+  Servo_ScopeRule_GetCssText(mRawRule.get(), &aCssText);
+}
+
+void CSSScopeRule::GetStart(nsACString& aStart) const {
+  Servo_ScopeRule_GetStart(mRawRule.get(), &aStart);
+}
+
+void CSSScopeRule::GetEnd(nsACString& aEnd) const {
+  Servo_ScopeRule_GetEnd(mRawRule.get(), &aEnd);
+}
+
+size_t CSSScopeRule::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(this);
+}
+
+JSObject* CSSScopeRule::WrapObject(JSContext* aCx,
+                                   JS::Handle<JSObject*> aGivenProto) {
+  return CSSScopeRule_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom
diff --git a/layout/style/CSSScopeRule.h b/layout/style/CSSScopeRule.h
new file mode 100644
index 0000000000..2cb1fa7e40
--- /dev/null
+++ b/layout/style/CSSScopeRule.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CSSScopeRule_h___
+#define CSSScopeRule_h___
+
+#include "mozilla/css/GroupRule.h"
+#include "mozilla/ServoBindingTypes.h"
+
+namespace mozilla::dom {
+
+class CSSScopeRule final : public css::GroupRule {
+ public:
+  CSSScopeRule(RefPtr<StyleScopeRule> aRawRule, StyleSheet* aSheet,
+               css::Rule* aParentRule, uint32_t aLine, uint32_t aColumn);
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+#ifdef DEBUG
+  void List(FILE* out = stdout, int32_t aIndent = 0) const final;
+#endif
+
+  StyleScopeRule* Raw() const { return mRawRule; }
+  void SetRawAfterClone(RefPtr<StyleScopeRule>);
+
+  already_AddRefed<StyleLockedCssRules> GetOrCreateRawRules() final;
+
+  // WebIDL interface
+  StyleCssRuleType Type() const final;
+  void GetCssText(nsACString& aCssText) const final;
+
+  void GetStart(nsACString& aStart) const;
+  void GetEnd(nsACString& aEnd) const;
+
+  size_t SizeOfIncludingThis(MallocSizeOf) const override;
+  JSObject* WrapObject(JSContext*, JS::Handle<JSObject*>) override;
+
+ private:
+  ~CSSScopeRule() = default;
+
+  RefPtr<StyleScopeRule> mRawRule;
+};
+
+}  // namespace mozilla::dom
+
+#endif
diff --git a/layout/style/CSSStartingStyleRule.cpp b/layout/style/CSSStartingStyleRule.cpp
new file mode 100644
index 0000000000..5c5ec311c9
--- /dev/null
+++ b/layout/style/CSSStartingStyleRule.cpp
@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/CSSStartingStyleRule.h"
+#include "mozilla/dom/CSSStartingStyleRuleBinding.h"
+#include "mozilla/ServoBindings.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(CSSStartingStyleRule,
+                                               css::GroupRule)
+
+// QueryInterface implementation for SupportsRule
+
+#ifdef DEBUG
+void CSSStartingStyleRule::List(FILE* out, int32_t aIndent) const {
+  nsAutoCString str;
+  for (int32_t i = 0; i < aIndent; i++) {
+    str.AppendLiteral("  ");
+  }
+  Servo_StartingStyleRule_Debug(mRawRule, &str);
+  fprintf_stderr(out, "%s\n", str.get());
+}
+#endif
+
+StyleCssRuleType CSSStartingStyleRule::Type() const {
+  return StyleCssRuleType::StartingStyle;
+}
+
+already_AddRefed<StyleLockedCssRules>
+CSSStartingStyleRule::GetOrCreateRawRules() {
+  return Servo_StartingStyleRule_GetRules(mRawRule).Consume();
+}
+
+void CSSStartingStyleRule::GetCssText(nsACString& aCssText) const {
+  Servo_StartingStyleRule_GetCssText(mRawRule.get(), &aCssText);
+}
+
+JSObject* CSSStartingStyleRule::WrapObject(JSContext* aCx,
+                                           JS::Handle<JSObject*> aGivenProto) {
+  return CSSStartingStyleRule_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom
diff --git a/layout/style/CSSStartingStyleRule.h b/layout/style/CSSStartingStyleRule.h
new file mode 100644
index 0000000000..9ecccf505c
--- /dev/null
+++ b/layout/style/CSSStartingStyleRule.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CSSStaringStyleRule_h___
+#define CSSStaringStyleRule_h___
+
+#include "mozilla/css/GroupRule.h"
+#include "mozilla/ServoBindingTypes.h"
+
+namespace mozilla::dom {
+
+class CSSStartingStyleRule final : public css::GroupRule {
+ public:
+  CSSStartingStyleRule(RefPtr<StyleStartingStyleRule> aRawRule,
+                       StyleSheet* aSheet, css::Rule* aParentRule,
+                       uint32_t aLine, uint32_t aColumn)
+      : css::GroupRule(aSheet, aParentRule, aLine, aColumn),
+        mRawRule(std::move(aRawRule)) {}
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+#ifdef DEBUG
+  void List(FILE* out = stdout, int32_t aIndent = 0) const final;
+#endif
+
+  StyleStartingStyleRule* Raw() const { return mRawRule; }
+  void SetRawAfterClone(RefPtr<StyleStartingStyleRule> aRaw) {
+    mRawRule = std::move(aRaw);
+    css::GroupRule::DidSetRawAfterClone();
+  }
+
+  already_AddRefed<StyleLockedCssRules> GetOrCreateRawRules() final;
+
+  // WebIDL interface
+  StyleCssRuleType Type() const final;
+  void GetCssText(nsACString& aCssText) const final;
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+  JSObject* WrapObject(JSContext*, JS::Handle<JSObject*>) override;
+
+ private:
+  ~CSSStartingStyleRule() = default;
+
+  RefPtr<StyleStartingStyleRule> mRawRule;
+};
+
+}  // namespace mozilla::dom
+
+#endif
diff --git a/layout/style/FontFaceImpl.cpp b/layout/style/FontFaceImpl.cpp
index 9d1f7c8c5b..5650b62afd 100644
--- a/layout/style/FontFaceImpl.cpp
+++ b/layout/style/FontFaceImpl.cpp
@@ -675,25 +675,40 @@ bool FontFaceImpl::IsInFontFaceSet(FontFaceSetImpl* aFontFaceSet) const {
 void FontFaceImpl::AddFontFaceSet(FontFaceSetImpl* aFontFaceSet) {
   MOZ_ASSERT(!IsInFontFaceSet(aFontFaceSet));
 
-  if (mFontFaceSet == aFontFaceSet) {
-    mInFontFaceSet = true;
+  auto doAddFontFaceSet = [&]() {
+    if (mFontFaceSet == aFontFaceSet) {
+      mInFontFaceSet = true;
+    } else {
+      mOtherFontFaceSets.AppendElement(aFontFaceSet);
+    }
+  };
+
+  if (mUserFontEntry) {
+    AutoWriteLock lock(mUserFontEntry->Lock());
+    doAddFontFaceSet();
   } else {
-    mOtherFontFaceSets.AppendElement(aFontFaceSet);
+    doAddFontFaceSet();
   }
 }
 
 void FontFaceImpl::RemoveFontFaceSet(FontFaceSetImpl* aFontFaceSet) {
   MOZ_ASSERT(IsInFontFaceSet(aFontFaceSet));
 
-  if (mFontFaceSet == aFontFaceSet) {
-    mInFontFaceSet = false;
-  } else {
-    mOtherFontFaceSets.RemoveElement(aFontFaceSet);
-  }
+  auto doRemoveFontFaceSet = [&]() {
+    if (mFontFaceSet == aFontFaceSet) {
+      mInFontFaceSet = false;
+    } else {
+      mOtherFontFaceSets.RemoveElement(aFontFaceSet);
+    }
+  };
 
-  // The caller should be holding a strong reference to the FontFaceSetImpl.
   if (mUserFontEntry) {
-    mUserFontEntry->CheckUserFontSet();
+    AutoWriteLock lock(mUserFontEntry->Lock());
+    doRemoveFontFaceSet();
+    // The caller should be holding a strong reference to the FontFaceSetImpl.
+    mUserFontEntry->CheckUserFontSetLocked();
+  } else {
+    doRemoveFontFaceSet();
   }
 }
 
@@ -736,7 +751,7 @@ void FontFaceImpl::Entry::SetLoadState(UserFontLoadState aLoadState) {
 
   nsTArray<RefPtr<FontFaceImpl>> fontFaces;
   {
-    MutexAutoLock lock(mMutex);
+    AutoReadLock lock(mLock);
     fontFaces.SetCapacity(mFontFaces.Length());
     for (FontFaceImpl* f : mFontFaces) {
       fontFaces.AppendElement(f);
@@ -758,7 +773,7 @@ void FontFaceImpl::Entry::SetLoadState(UserFontLoadState aLoadState) {
 /* virtual */
 void FontFaceImpl::Entry::GetUserFontSets(
     nsTArray<RefPtr<gfxUserFontSet>>& aResult) {
-  MutexAutoLock lock(mMutex);
+  AutoReadLock lock(mLock);
 
   aResult.Clear();
 
@@ -783,7 +798,7 @@ void FontFaceImpl::Entry::GetUserFontSets(
 
 /* virtual */ already_AddRefed<gfxUserFontSet>
 FontFaceImpl::Entry::GetUserFontSet() const {
-  MutexAutoLock lock(mMutex);
+  AutoReadLock lock(mLock);
   if (mFontSet) {
     return do_AddRef(mFontSet);
   }
@@ -816,7 +831,7 @@ void FontFaceImpl::Entry::CheckUserFontSetLocked() {
 }
 
 void FontFaceImpl::Entry::FindFontFaceOwners(nsTHashSet<FontFace*>& aOwners) {
-  MutexAutoLock lock(mMutex);
+  AutoReadLock lock(mLock);
   for (FontFaceImpl* f : mFontFaces) {
     if (FontFace* owner = f->GetOwner()) {
       aOwners.Insert(owner);
@@ -825,13 +840,13 @@ void FontFaceImpl::Entry::FindFontFaceOwners(nsTHashSet<FontFace*>& aOwners) {
 }
 
 void FontFaceImpl::Entry::AddFontFace(FontFaceImpl* aFontFace) {
-  MutexAutoLock lock(mMutex);
+  AutoWriteLock lock(mLock);
   mFontFaces.AppendElement(aFontFace);
   CheckUserFontSetLocked();
 }
 
 void FontFaceImpl::Entry::RemoveFontFace(FontFaceImpl* aFontFace) {
-  MutexAutoLock lock(mMutex);
+  AutoWriteLock lock(mLock);
   mFontFaces.RemoveElement(aFontFace);
   CheckUserFontSetLocked();
 }
diff --git a/layout/style/FontFaceImpl.h b/layout/style/FontFaceImpl.h
index 70c06609e9..7f1279a248 100644
--- a/layout/style/FontFaceImpl.h
+++ b/layout/style/FontFaceImpl.h
@@ -10,7 +10,7 @@
 #include "mozilla/dom/FontFaceBinding.h"
 #include "mozilla/FontPropertyTypes.h"
 #include "mozilla/Maybe.h"
-#include "mozilla/Mutex.h"
+#include "mozilla/RWLock.h"
 #include "mozilla/ServoStyleConsts.h"
 #include "gfxUserFontSet.h"
 #include "nsCSSPropertyID.h"
@@ -50,21 +50,15 @@ class FontFaceImpl final {
     Entry(gfxUserFontSet* aFontSet, nsTArray<gfxFontFaceSrc>&& aFontFaceSrcList,
           gfxUserFontAttributes&& aAttr)
         : gfxUserFontEntry(std::move(aFontFaceSrcList), std::move(aAttr)),
-          mMutex("FontFaceImpl::Entry::mMutex"),
           mFontSet(aFontSet) {}
 
     void SetLoadState(UserFontLoadState aLoadState) override;
     void GetUserFontSets(nsTArray<RefPtr<gfxUserFontSet>>& aResult) override;
     already_AddRefed<gfxUserFontSet> GetUserFontSet() const override;
 
-    void CheckUserFontSet() {
-      MutexAutoLock lock(mMutex);
-      CheckUserFontSetLocked();
-    }
-
 #ifdef DEBUG
     bool HasUserFontSet(gfxUserFontSet* aFontSet) const {
-      MutexAutoLock lock(mMutex);
+      AutoReadLock lock(mLock);
       return mFontSet == aFontSet;
     }
 #endif
@@ -73,19 +67,19 @@ class FontFaceImpl final {
     void RemoveFontFace(FontFaceImpl* aOwner);
     void FindFontFaceOwners(nsTHashSet<FontFace*>& aOwners);
 
-   protected:
-    void CheckUserFontSetLocked() MOZ_REQUIRES(mMutex);
+    RWLock& Lock() const MOZ_RETURN_CAPABILITY(mLock) { return mLock; }
 
-    mutable Mutex mMutex;
+   protected:
+    void CheckUserFontSetLocked() MOZ_REQUIRES(mLock);
 
     // Font set which owns this entry;
-    gfxUserFontSet* MOZ_NON_OWNING_REF mFontSet MOZ_GUARDED_BY(mMutex);
+    gfxUserFontSet* MOZ_NON_OWNING_REF mFontSet MOZ_GUARDED_BY(mLock);
 
     // The FontFace objects that use this user font entry.  We need to store
     // an array of these, not just a single pointer, since the user font
     // cache can return the same entry for different FontFaces that have
     // the same descriptor values and come from the same origin.
-    AutoTArray<FontFaceImpl*, 1> mFontFaces MOZ_GUARDED_BY(mMutex);
+    AutoTArray<FontFaceImpl*, 1> mFontFaces MOZ_GUARDED_BY(mLock);
   };
 
 #ifdef DEBUG
diff --git a/layout/style/FontFaceSetDocumentImpl.cpp b/layout/style/FontFaceSetDocumentImpl.cpp
index 33f7404c7c..cd1d5959d2 100644
--- a/layout/style/FontFaceSetDocumentImpl.cpp
+++ b/layout/style/FontFaceSetDocumentImpl.cpp
@@ -496,7 +496,7 @@ bool FontFaceSetDocumentImpl::UpdateRules(
   }
 
   if (modified) {
-    IncrementGeneration(true);
+    IncrementGenerationLocked(true);
     mHasLoadingFontFacesIsDirty = true;
     CheckLoadingStarted();
     CheckLoadingFinished();
diff --git a/layout/style/FontFaceSetImpl.cpp b/layout/style/FontFaceSetImpl.cpp
index 7383842a41..5dabf25d38 100644
--- a/layout/style/FontFaceSetImpl.cpp
+++ b/layout/style/FontFaceSetImpl.cpp
@@ -70,8 +70,7 @@ using namespace mozilla::dom;
 NS_IMPL_ISUPPORTS0(FontFaceSetImpl)
 
 FontFaceSetImpl::FontFaceSetImpl(FontFaceSet* aOwner)
-    : mMutex("mozilla::dom::FontFaceSetImpl"),
-      mOwner(aOwner),
+    : mOwner(aOwner),
       mStatus(FontFaceSetLoadStatus::Loaded),
       mNonRuleFacesDirty(false),
       mHasLoadingFontFaces(false),
@@ -891,7 +890,7 @@ void FontFaceSetImpl::OnLoadingFinished() {
 void FontFaceSetImpl::RefreshStandardFontLoadPrincipal() {
   RecursiveMutexAutoLock lock(mMutex);
   mAllowedFontLoads.Clear();
-  IncrementGeneration(false);
+  IncrementGenerationLocked(false);
 }
 
 // -- gfxUserFontSet
diff --git a/layout/style/FontFaceSetImpl.h b/layout/style/FontFaceSetImpl.h
index 6f245c6599..dd412dd721 100644
--- a/layout/style/FontFaceSetImpl.h
+++ b/layout/style/FontFaceSetImpl.h
@@ -92,9 +92,10 @@ class FontFaceSetImpl : public nsISupports, public gfxUserFontSet {
   virtual void DispatchToOwningThread(const char* aName,
                                       std::function<void()>&& aFunc) = 0;
 
-  // Called by nsFontFaceLoader when the loader has completed normally.
+  // Called by nsFontFaceLoader when the loader has completed normally,
+  // or by gfxUserFontSet if it cancels the loader.
   // It's removed from the mLoaders set.
-  virtual void RemoveLoader(nsFontFaceLoader* aLoader);
+  void RemoveLoader(nsFontFaceLoader* aLoader) override;
 
   virtual bool UpdateRules(const nsTArray<nsFontFaceRuleContainer>& aRules) {
     MOZ_ASSERT_UNREACHABLE("Not implemented!");
@@ -247,8 +248,6 @@ class FontFaceSetImpl : public nsISupports, public gfxUserFontSet {
 
   virtual TimeStamp GetNavigationStartTimeStamp() = 0;
 
-  mutable RecursiveMutex mMutex;
-
   FontFaceSet* MOZ_NON_OWNING_REF mOwner MOZ_GUARDED_BY(mMutex);
 
   // The document's node principal, which is the principal font loads for
diff --git a/layout/style/FontFaceSetWorkerImpl.cpp b/layout/style/FontFaceSetWorkerImpl.cpp
index 015c9e5b18..7fbfbf0d95 100644
--- a/layout/style/FontFaceSetWorkerImpl.cpp
+++ b/layout/style/FontFaceSetWorkerImpl.cpp
@@ -227,7 +227,7 @@ void FontFaceSetWorkerImpl::FlushUserFontSet() {
   }
 
   if (modified) {
-    IncrementGeneration(true);
+    IncrementGenerationLocked(true);
     mHasLoadingFontFacesIsDirty = true;
     CheckLoadingStarted();
     CheckLoadingFinished();
diff --git a/layout/style/GenerateServoCSSPropList.py b/layout/style/GenerateServoCSSPropList.py
index 0e9678ac5c..4dba1f0a8f 100644
--- a/layout/style/GenerateServoCSSPropList.py
+++ b/layout/style/GenerateServoCSSPropList.py
@@ -30,7 +30,7 @@ def generate_data(output, template):
     )
 
     # Add all relevant files into the dependencies of the generated file.
-    DEP_EXTS = [".py", ".rs", ".zip"]
+    DEP_EXTS = [".py", ".rs"]
     deps = set()
     for path, dirs, files in os.walk(SERVO_PROP_BASE):
         for file in files:
diff --git a/layout/style/ImageLoader.cpp b/layout/style/ImageLoader.cpp
index 2ae1822b02..1a59a5bcf3 100644
--- a/layout/style/ImageLoader.cpp
+++ b/layout/style/ImageLoader.cpp
@@ -565,6 +565,16 @@ static void InvalidateImages(nsIFrame* aFrame, imgIRequest* aRequest,
       }
     }
   }
+#ifdef XP_MACOSX
+  else if (aFrame->HasAnyStateBits(NS_FRAME_IN_POPUP)) {
+    // On macOS popups are painted with fallback rendering so they don't have
+    // webrender user data to tell us if the frame was painted last time, so we
+    // just have to invalidate always. Bug 1754796 tracks making popups on macOS
+    // use webrender. (On other platforms tooltips type popups are still
+    // rendered with fallback, but we don't expect them to have images.)
+    invalidateFrame = true;
+  }
+#endif
 
   // Update ancestor rendering observers (-moz-element etc)
   //
diff --git a/layout/style/PreferenceSheet.cpp b/layout/style/PreferenceSheet.cpp
index a206209885..eb752b2789 100644
--- a/layout/style/PreferenceSheet.cpp
+++ b/layout/style/PreferenceSheet.cpp
@@ -205,7 +205,7 @@ void PreferenceSheet::Prefs::Load(bool aIsChrome) {
   // as those are the colors exposed to the user in the colors dialog.
   mMustUseLightColorSet = mUsePrefColors && !mUseDocumentColors;
 #ifdef XP_WIN
-  if (mUseAccessibilityTheme) {
+  if (mUseAccessibilityTheme && (mIsChrome || !mUseDocumentColors)) {
     // Windows overrides the light colors with the HCM colors when HCM is
     // active, so make sure to always use the light system colors in that case,
     // and also make sure that we always use the light color set for the same
diff --git a/layout/style/Rule.cpp b/layout/style/Rule.cpp
index 0a7de42789..4b0f783bd9 100644
--- a/layout/style/Rule.cpp
+++ b/layout/style/Rule.cpp
@@ -106,7 +106,9 @@ void Rule::AssertParentRuleType() {
                type == StyleCssRuleType::Supports ||
                type == StyleCssRuleType::Keyframes ||
                type == StyleCssRuleType::LayerBlock ||
-               type == StyleCssRuleType::Container);
+               type == StyleCssRuleType::Container ||
+               type == StyleCssRuleType::Scope ||
+               type == StyleCssRuleType::StartingStyle);
   }
 }
 #endif
diff --git a/layout/style/ServoBindingTypes.h b/layout/style/ServoBindingTypes.h
index fe4f96cf0b..b081a4981b 100644
--- a/layout/style/ServoBindingTypes.h
+++ b/layout/style/ServoBindingTypes.h
@@ -129,6 +129,8 @@ UNLOCKED_RULE_TYPE(Supports)
 UNLOCKED_RULE_TYPE(Document)
 UNLOCKED_RULE_TYPE(FontFeatureValues)
 UNLOCKED_RULE_TYPE(FontPaletteValues)
+UNLOCKED_RULE_TYPE(Scope)
+UNLOCKED_RULE_TYPE(StartingStyle)
 
 SERVO_ARC_TYPE(AnimationValue, mozilla::StyleAnimationValue)
 SERVO_ARC_TYPE(ComputedStyle, mozilla::ComputedStyle)
diff --git a/layout/style/ServoBindings.h b/layout/style/ServoBindings.h
index 6f19006512..52538cafb8 100644
--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -77,7 +77,7 @@ BASIC_RULE_FUNCS_LOCKED(Keyframes)
 GROUP_RULE_FUNCS_UNLOCKED(Media)
 GROUP_RULE_FUNCS_UNLOCKED(Document)
 BASIC_RULE_FUNCS_UNLOCKED(Namespace)
-BASIC_RULE_FUNCS_LOCKED(Page)
+GROUP_RULE_FUNCS_LOCKED(Page)
 BASIC_RULE_FUNCS_UNLOCKED(Property)
 GROUP_RULE_FUNCS_UNLOCKED(Supports)
 GROUP_RULE_FUNCS_UNLOCKED(LayerBlock)
@@ -87,6 +87,8 @@ BASIC_RULE_FUNCS_UNLOCKED(FontPaletteValues)
 BASIC_RULE_FUNCS_LOCKED(FontFace)
 BASIC_RULE_FUNCS_LOCKED(CounterStyle)
 GROUP_RULE_FUNCS_UNLOCKED(Container)
+GROUP_RULE_FUNCS_UNLOCKED(Scope)
+GROUP_RULE_FUNCS_UNLOCKED(StartingStyle)
 
 #undef GROUP_RULE_FUNCS_LOCKED
 #undef GROUP_RULE_FUNCS_UNLOCKED
diff --git a/layout/style/ServoBindings.toml b/layout/style/ServoBindings.toml
index 20e1ca4116..67fd902e2b 100644
--- a/layout/style/ServoBindings.toml
+++ b/layout/style/ServoBindings.toml
@@ -515,6 +515,9 @@ cbindgen-types = [
     { gecko = "StyleBasicShape", servo = "crate::values::computed::basic_shape::BasicShape" },
     { gecko = "StyleGenericInsetRect", servo = "crate::values::generics::basic_shape::InsetRect" },
     { gecko = "StyleInsetRect", servo = "crate::values::computed::basic_shape::InsetRect" },
+    { gecko = "StyleShape", servo = "crate::values::computed::basic_shape::Shape" },
+    { gecko = "StyleShapeCommand", servo = "crate::values::computed::basic_shape::ShapeCommand" },
+    { gecko = "StyleGenericShapeCommand", servo = "crate::values::generics::basic_shape::ShapeCommand" },
     { gecko = "StyleArcSlice", servo = "style_traits::arc_slice::ArcSlice" },
     { gecko = "StyleForgottenArcSlicePtr", servo = "style_traits::arc_slice::ForgottenArcSlicePtr" },
     { gecko = "StyleOwnedSlice", servo = "style_traits::owned_slice::OwnedSlice" },
diff --git a/layout/style/ServoCSSRuleList.cpp b/layout/style/ServoCSSRuleList.cpp
index 6fcdfdd4b5..133a962256 100644
--- a/layout/style/ServoCSSRuleList.cpp
+++ b/layout/style/ServoCSSRuleList.cpp
@@ -22,6 +22,8 @@
 #include "mozilla/dom/CSSNamespaceRule.h"
 #include "mozilla/dom/CSSPageRule.h"
 #include "mozilla/dom/CSSPropertyRule.h"
+#include "mozilla/dom/CSSScopeRule.h"
+#include "mozilla/dom/CSSStartingStyleRule.h"
 #include "mozilla/dom/CSSStyleRule.h"
 #include "mozilla/dom/CSSSupportsRule.h"
 #include "mozilla/IntegerRange.h"
@@ -98,6 +100,8 @@ css::Rule* ServoCSSRuleList::GetRule(uint32_t aIndex) {
       CASE_RULE_UNLOCKED(LayerBlock, LayerBlock)
       CASE_RULE_UNLOCKED(LayerStatement, LayerStatement)
       CASE_RULE_UNLOCKED(Container, Container)
+      CASE_RULE_UNLOCKED(Scope, Scope)
+      CASE_RULE_UNLOCKED(StartingStyle, StartingStyle)
 #undef CASE_RULE_LOCKED
 #undef CASE_RULE_UNLOCKED
 #undef CASE_RULE_WITH_PREFIX
@@ -208,12 +212,21 @@ nsresult ServoCSSRuleList::InsertRule(const nsACString& aRule,
   }
   StyleCssRuleType type;
   uint32_t containingTypes = 0;
+  Maybe<StyleCssRuleType> parseRelativeRuleType;
   for (css::Rule* rule = mParentRule; rule; rule = rule->GetParentRule()) {
-    containingTypes |= (1 << uint32_t(rule->Type()));
+    const auto ruleType = rule->Type();
+    containingTypes |= (1 << uint32_t(ruleType));
+    if (parseRelativeRuleType.isNothing() &&
+        (ruleType == StyleCssRuleType::Style ||
+         ruleType == StyleCssRuleType::Scope)) {
+      // Only the closest applicable type to this rule matters.
+      parseRelativeRuleType = Some(ruleType);
+    }
   }
   nsresult rv = Servo_CssRules_InsertRule(
       mRawRules, mStyleSheet->RawContents(), &aRule, aIndex, containingTypes,
-      loader, allowImportRules, mStyleSheet, &type);
+      parseRelativeRuleType.ptrOr(nullptr), loader, allowImportRules,
+      mStyleSheet, &type);
   NS_ENSURE_SUCCESS(rv, rv);
   mRules.InsertElementAt(aIndex, uintptr_t(type));
   return rv;
@@ -276,6 +289,8 @@ void ServoCSSRuleList::SetRawContents(RefPtr<StyleLockedCssRules> aNewRules,
       RULE_CASE_UNLOCKED(LayerBlock, LayerBlock)
       RULE_CASE_UNLOCKED(LayerStatement, LayerStatement)
       RULE_CASE_UNLOCKED(Container, Container)
+      RULE_CASE_UNLOCKED(Scope, Scope)
+      RULE_CASE_UNLOCKED(StartingStyle, StartingStyle)
       case StyleCssRuleType::Keyframe:
         MOZ_ASSERT_UNREACHABLE("keyframe rule cannot be here");
         break;
diff --git a/layout/style/ServoElementSnapshot.cpp b/layout/style/ServoElementSnapshot.cpp
index e0ef2849f9..a5251d9349 100644
--- a/layout/style/ServoElementSnapshot.cpp
+++ b/layout/style/ServoElementSnapshot.cpp
@@ -82,4 +82,11 @@ void ServoElementSnapshot::AddAttrs(const Element& aElement,
   }
 }
 
+void ServoElementSnapshot::AddCustomStates(Element& aElement) {
+  if (mContains & Flags::CustomState) {
+    return;
+  }
+  mCustomStates = aElement.EnsureCustomStates().Clone();
+  mContains |= Flags::CustomState;
+}
 }  // namespace mozilla
diff --git a/layout/style/ServoElementSnapshot.h b/layout/style/ServoElementSnapshot.h
index b702975c4b..5a86b4c13d 100644
--- a/layout/style/ServoElementSnapshot.h
+++ b/layout/style/ServoElementSnapshot.h
@@ -33,6 +33,7 @@ enum class ServoElementSnapshotFlags : uint8_t {
   Id = 1 << 2,
   MaybeClass = 1 << 3,
   OtherPseudoClassState = 1 << 4,
+  CustomState = 1 << 5,
 };
 
 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(ServoElementSnapshotFlags)
@@ -89,6 +90,11 @@ class ServoElementSnapshot {
   void AddAttrs(const Element&, int32_t aNameSpaceID, nsAtom* aAttribute);
 
   /**
+   * Captures the given element custom states.
+   */
+  void AddCustomStates(Element&);
+
+  /**
    * Captures some other pseudo-class matching state not included in
    * ElementState.
    */
@@ -155,6 +161,7 @@ class ServoElementSnapshot {
   // snapshots.
   nsTArray<AttrArray::InternalAttr> mAttrs;
   nsTArray<RefPtr<nsAtom>> mChangedAttrNames;
+  nsTArray<RefPtr<nsAtom>> mCustomStates;
   nsAttrValue mClass;
   ServoStateType mState;
   Flags mContains;
diff --git a/layout/style/ServoStyleConstsForwards.h b/layout/style/ServoStyleConstsForwards.h
index 65128e1377..5bf87d8330 100644
--- a/layout/style/ServoStyleConstsForwards.h
+++ b/layout/style/ServoStyleConstsForwards.h
@@ -83,7 +83,7 @@ struct PropertyStyleAnimationValuePair;
 using ComputedKeyframeValues = nsTArray<PropertyStyleAnimationValuePair>;
 
 class ComputedStyle;
-enum LogicalAxis : uint8_t;
+enum class LogicalAxis : uint8_t;
 class SeenPtrs;
 class SharedFontList;
 class StyleSheet;
@@ -100,7 +100,7 @@ struct ComputedTiming;
 struct URLExtraData;
 
 enum HalfCorner : uint8_t;
-enum LogicalSide : uint8_t;
+enum class LogicalSide : uint8_t;
 enum class PseudoStyleType : uint8_t;
 enum class OriginFlags : uint8_t;
 enum class UseBoxSizing : uint8_t;
diff --git a/layout/style/ServoStyleConstsInlines.h b/layout/style/ServoStyleConstsInlines.h
index 1985e8fbeb..5a86e4ccd0 100644
--- a/layout/style/ServoStyleConstsInlines.h
+++ b/layout/style/ServoStyleConstsInlines.h
@@ -53,6 +53,8 @@ template struct StyleStrong<StyleFontPaletteValuesRule>;
 template struct StyleStrong<StyleLockedFontFaceRule>;
 template struct StyleStrong<StyleLockedCounterStyleRule>;
 template struct StyleStrong<StyleContainerRule>;
+template struct StyleStrong<StyleScopeRule>;
+template struct StyleStrong<StyleStartingStyleRule>;
 
 template <typename T>
 inline void StyleOwnedSlice<T>::Clear() {
@@ -697,9 +699,12 @@ CSSCoord StyleCalcLengthPercentage::ResolveToCSSPixels(CSSCoord aBasis) const {
   return Servo_ResolveCalcLengthPercentage(this, aBasis);
 }
 
-nscoord StyleCalcLengthPercentage::Resolve(nscoord aBasis) const {
-  return detail::DefaultLengthToAppUnits(
-      ResolveToCSSPixels(CSSPixel::FromAppUnits(aBasis)));
+template <typename Rounder>
+nscoord StyleCalcLengthPercentage::Resolve(nscoord aBasis,
+                                           Rounder aRounder) const {
+  static_assert(std::is_same_v<decltype(aRounder(1.0f)), nscoord>);
+  CSSCoord result = ResolveToCSSPixels(CSSPixel::FromAppUnits(aBasis));
+  return aRounder(result * AppUnitsPerCSSPixel());
 }
 
 template <>
@@ -724,11 +729,10 @@ CSSCoord LengthPercentage::ResolveToCSSPixelsWith(T aPercentageGetter) const {
   return ResolveToCSSPixels(aPercentageGetter());
 }
 
-template <typename T, typename PercentRounder>
-nscoord LengthPercentage::Resolve(T aPercentageGetter,
-                                  PercentRounder aPercentRounder) const {
+template <typename T, typename Rounder>
+nscoord LengthPercentage::Resolve(T aPercentageGetter, Rounder aRounder) const {
   static_assert(std::is_same_v<decltype(aPercentageGetter()), nscoord>);
-  static_assert(std::is_same_v<decltype(aPercentRounder(1.0f)), nscoord>);
+  static_assert(std::is_same_v<decltype(aRounder(1.0f)), nscoord>);
   if (ConvertsToLength()) {
     return ToLength();
   }
@@ -737,9 +741,9 @@ nscoord LengthPercentage::Resolve(T aPercentageGetter,
   }
   nscoord basis = aPercentageGetter();
   if (IsPercentage()) {
-    return aPercentRounder(basis * AsPercentage()._0);
+    return aRounder(basis * AsPercentage()._0);
   }
-  return AsCalc().Resolve(basis);
+  return AsCalc().Resolve(basis, aRounder);
 }
 
 nscoord LengthPercentage::Resolve(nscoord aPercentageBasis) const {
@@ -752,11 +756,10 @@ nscoord LengthPercentage::Resolve(T aPercentageGetter) const {
   return Resolve(aPercentageGetter, detail::DefaultPercentLengthToAppUnits);
 }
 
-template <typename PercentRounder>
+template <typename Rounder>
 nscoord LengthPercentage::Resolve(nscoord aPercentageBasis,
-                                  PercentRounder aPercentRounder) const {
-  return Resolve([aPercentageBasis] { return aPercentageBasis; },
-                 aPercentRounder);
+                                  Rounder aRounder) const {
+  return Resolve([aPercentageBasis] { return aPercentageBasis; }, aRounder);
 }
 
 void LengthPercentage::ScaleLengthsBy(float aScale) {
@@ -1201,6 +1204,20 @@ inline nsRect StyleZoom::Unzoom(const nsRect& aValue) const {
                 UnzoomCoord(aValue.Width()), UnzoomCoord(aValue.Height()));
 }
 
+template <>
+inline gfx::Point StyleCoordinatePair<StyleCSSFloat>::ToGfxPoint(
+    const CSSSize* aBasis) const {
+  return gfx::Point(x, y);
+}
+
+template <>
+inline gfx::Point StyleCoordinatePair<LengthPercentage>::ToGfxPoint(
+    const CSSSize* aBasis) const {
+  MOZ_ASSERT(aBasis);
+  return gfx::Point(x.ResolveToCSSPixels(aBasis->Width()),
+                    y.ResolveToCSSPixels(aBasis->Height()));
+}
+
 }  // namespace mozilla
 
 #endif
diff --git a/layout/style/ServoStyleSet.cpp b/layout/style/ServoStyleSet.cpp
index cfc38849b8..91231af2b0 100644
--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -41,7 +41,9 @@
 #include "mozilla/dom/CSSNamespaceRule.h"
 #include "mozilla/dom/CSSPageRule.h"
 #include "mozilla/dom/CSSPropertyRule.h"
+#include "mozilla/dom/CSSScopeRule.h"
 #include "mozilla/dom/CSSSupportsRule.h"
+#include "mozilla/dom/CSSStartingStyleRule.h"
 #include "mozilla/dom/FontFaceSet.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ElementInlines.h"
@@ -1002,6 +1004,8 @@ void ServoStyleSet::RuleChangedInternal(StyleSheet& aSheet, css::Rule& aRule,
     CASE_FOR(LayerBlock, LayerBlock)
     CASE_FOR(LayerStatement, LayerStatement)
     CASE_FOR(Container, Container)
+    CASE_FOR(Scope, Scope)
+    CASE_FOR(StartingStyle, StartingStyle)
     // @namespace can only be inserted / removed when there are only other
     // @namespace and @import rules, and can't be mutated.
     case StyleCssRuleType::Namespace:
@@ -1394,6 +1398,13 @@ void ServoStyleSet::MaybeInvalidateRelativeSelectorClassDependency(
       mRawData.get(), &aElement, &aSnapshots);
 }
 
+void ServoStyleSet::MaybeInvalidateRelativeSelectorCustomStateDependency(
+    const Element& aElement, nsAtom* state,
+    const ServoElementSnapshotTable& aSnapshots) {
+  Servo_StyleSet_MaybeInvalidateRelativeSelectorCustomStateDependency(
+      mRawData.get(), &aElement, state, &aSnapshots);
+}
+
 void ServoStyleSet::MaybeInvalidateRelativeSelectorAttributeDependency(
     const Element& aElement, nsAtom* aAttribute,
     const ServoElementSnapshotTable& aSnapshots) {
@@ -1465,6 +1476,12 @@ bool ServoStyleSet::HasNthOfStateDependency(const Element& aElement,
                                                 aState.GetInternalValue());
 }
 
+bool ServoStyleSet::HasNthOfCustomStateDependency(const Element& aElement,
+                                                  nsAtom* aState) const {
+  return Servo_StyleSet_HasNthOfCustomStateDependency(mRawData.get(), &aElement,
+                                                      aState);
+}
+
 void ServoStyleSet::RestyleSiblingsForNthOf(const Element& aElement,
                                             uint32_t aFlags) const {
   Servo_StyleSet_RestyleSiblingsForNthOf(&aElement, aFlags);
diff --git a/layout/style/ServoStyleSet.h b/layout/style/ServoStyleSet.h
index eee6cba0f7..f3159c97ec 100644
--- a/layout/style/ServoStyleSet.h
+++ b/layout/style/ServoStyleSet.h
@@ -477,6 +477,14 @@ class ServoStyleSet {
       const dom::Element&, const ServoElementSnapshotTable& aSnapshots);
 
   /**
+   * Maybe invalidate if a modification to a Custom State might require us to
+   * restyle the relative selector it refers to.
+   */
+  void MaybeInvalidateRelativeSelectorCustomStateDependency(
+      const dom::Element&, nsAtom* state,
+      const ServoElementSnapshotTable& aSnapshots);
+
+  /**
    * Maybe invalidate if a modification to an ID might require us to restyle
    * the relative selector it refers to.
    */
@@ -550,6 +558,12 @@ class ServoStyleSet {
   bool HasNthOfStateDependency(const dom::Element&, dom::ElementState) const;
 
   /**
+   * Returns true if a change in Custom State on an element might require
+   * us to restyle the element's siblings.
+   */
+  bool HasNthOfCustomStateDependency(const dom::Element&, nsAtom*) const;
+
+  /**
    * Restyle this element's siblings in order to propagate any potential change
    * in :nth-child(of) styling.
    */
diff --git a/layout/style/SharedSubResourceCache.h b/layout/style/SharedSubResourceCache.h
index 32919b8863..896eacbcb5 100644
--- a/layout/style/SharedSubResourceCache.h
+++ b/layout/style/SharedSubResourceCache.h
@@ -58,6 +58,9 @@ struct SharedSubResourceCacheLoadingValueBase {
   virtual void SetLoadCompleted() = 0;
   virtual void Cancel() = 0;
 
+  // Return the next sub-resource which has the same key.
+  Derived* GetNextSubResource() { return mNext; }
+
   ~SharedSubResourceCacheLoadingValueBase() {
     // Do this iteratively to avoid blowing up the stack.
     RefPtr<Derived> next = std::move(mNext);
diff --git a/layout/style/moz.build b/layout/style/moz.build
index a14ab6a7ac..b77fa34983 100644
--- a/layout/style/moz.build
+++ b/layout/style/moz.build
@@ -56,6 +56,7 @@ EXPORTS += [
     "nsCSSValue.h",
     "nsDOMCSSAttrDeclaration.h",
     "nsDOMCSSDeclaration.h",
+    "nsFontFaceLoader.h",
     "nsICSSDeclaration.h",
     "nsICSSLoaderObserver.h",
     "nsStyleAutoArray.h",
@@ -143,6 +144,8 @@ EXPORTS.mozilla.dom += [
     "CSSPageRule.h",
     "CSSPropertyRule.h",
     "CSSRuleList.h",
+    "CSSScopeRule.h",
+    "CSSStartingStyleRule.h",
     "CSSStyleRule.h",
     "CSSSupportsRule.h",
     "CSSValue.h",
@@ -194,6 +197,8 @@ UNIFIED_SOURCES += [
     "CSSPageRule.cpp",
     "CSSPropertyRule.cpp",
     "CSSRuleList.cpp",
+    "CSSScopeRule.cpp",
+    "CSSStartingStyleRule.cpp",
     "CSSStyleRule.cpp",
     "CSSSupportsRule.cpp",
     "DeclarationBlock.cpp",
diff --git a/layout/style/nsCSSPseudoElementList.h b/layout/style/nsCSSPseudoElementList.h
index 9514dd6c4b..7492523c58 100644
--- a/layout/style/nsCSSPseudoElementList.h
+++ b/layout/style/nsCSSPseudoElementList.h
@@ -51,6 +51,7 @@ CSS_PSEUDO_ELEMENT(highlight, ":highlight", 0)
 CSS_PSEUDO_ELEMENT(selection, ":selection",
                    CSS_PSEUDO_ELEMENT_CONTAINS_ELEMENTS)
 
+CSS_PSEUDO_ELEMENT(targetText, ":target-text", 0)
 // XXXbz should we really allow random content to style these?  Maybe
 // use our flags to prevent that?
 CSS_PSEUDO_ELEMENT(mozFocusInner, ":-moz-focus-inner", 0)
diff --git a/layout/style/nsCSSPseudoElements.h b/layout/style/nsCSSPseudoElements.h
index 9866fbfb7e..baeee9d4de 100644
--- a/layout/style/nsCSSPseudoElements.h
+++ b/layout/style/nsCSSPseudoElements.h
@@ -130,6 +130,8 @@ class nsCSSPseudoElements {
     switch (aType) {
       case Type::highlight:
         return mozilla::StaticPrefs::dom_customHighlightAPI_enabled();
+      case Type::targetText:
+        return mozilla::StaticPrefs::dom_text_fragments_enabled();
       case Type::sliderTrack:
       case Type::sliderThumb:
       case Type::sliderFill:
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index d40d4bc801..5b71ec54bf 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -1358,11 +1358,28 @@ already_AddRefed<nsROCSSPrimitiveValue> nsComputedDOMStyle::MatrixToCSSValue(
 
   /* Create a value to hold our result. */
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
   val->SetString(resultString);
   return val.forget();
 }
 
+already_AddRefed<nsROCSSPrimitiveValue> nsComputedDOMStyle::AppUnitsToCSSValue(
+    nscoord aAppUnits) {
+  return PixelsToCSSValue(CSSPixel::FromAppUnits(aAppUnits));
+}
+
+already_AddRefed<nsROCSSPrimitiveValue> nsComputedDOMStyle::PixelsToCSSValue(
+    float aPixels) {
+  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
+  SetValueToPixels(val, aPixels);
+  return val.forget();
+}
+
+void nsComputedDOMStyle::SetValueToPixels(nsROCSSPrimitiveValue* aValue,
+                                          float aPixels) {
+  MOZ_ASSERT(mComputedStyle);
+  aValue->SetPixels(mComputedStyle->EffectiveZoom().Unzoom(aPixels));
+}
+
 already_AddRefed<CSSValue> nsComputedDOMStyle::DoGetMozOsxFontSmoothing() {
   if (nsContentUtils::ShouldResistFingerprinting(
           mPresShell->GetPresContext()->GetDocShell(),
@@ -1614,9 +1631,7 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetGridTemplateColumnsRows(
   // Add any leading implicit tracks.
   if (serializeImplicit) {
     for (uint32_t i = 0; i < numLeadingImplicitTracks; ++i) {
-      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(trackSizes[i]);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(AppUnitsToCSSValue(trackSizes[i]));
     }
   }
 
@@ -1652,8 +1667,7 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetGridTemplateColumnsRows(
     for (uint32_t i = 0; i < repeatStart; i++) {
       AppendGridLineNames(valueList, aTrackInfo.mResolvedLineNames[i]);
       RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(*trackSizeIter++);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(AppUnitsToCSSValue(*trackSizeIter++));
     }
     auto lineNameIter = aTrackInfo.mResolvedLineNames.cbegin() + repeatStart;
     // Write the track names at the start of the repeat, including the names
@@ -1666,9 +1680,7 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetGridTemplateColumnsRows(
       // track).
       const nscoord firstRepeatTrackSize =
           (!aTrackInfo.mRemovedRepeatTracks[0]) ? *trackSizeIter++ : 0;
-      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(firstRepeatTrackSize);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(AppUnitsToCSSValue(firstRepeatTrackSize));
     }
     // Write the line names and track sizes inside the repeat, checking for
     // removed tracks (size 0).
@@ -1688,9 +1700,7 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetGridTemplateColumnsRows(
                  trackSizeIter != explicitTrackSizeEnd);
       const nscoord repeatTrackSize =
           (!aTrackInfo.mRemovedRepeatTracks[i]) ? *trackSizeIter++ : 0;
-      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(repeatTrackSize);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(AppUnitsToCSSValue(repeatTrackSize));
     }
     // The resolved line names include a single repetition of the auto-repeat
     // line names. Skip over those.
@@ -1698,9 +1708,7 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetGridTemplateColumnsRows(
     // Write out any more tracks after the repeat.
     while (trackSizeIter != explicitTrackSizeEnd) {
       AppendGridLineNames(valueList, *lineNameIter++);
-      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(*trackSizeIter++);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(AppUnitsToCSSValue(*trackSizeIter++));
     }
     // Write the final trailing line name.
     AppendGridLineNames(valueList, *lineNameIter++);
@@ -1711,18 +1719,15 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetGridTemplateColumnsRows(
       if (i == numExplicitTracks) {
         break;
       }
-      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(trackSizes[i + numLeadingImplicitTracks]);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(
+          AppUnitsToCSSValue(trackSizes[i + numLeadingImplicitTracks]));
     }
   }
   // Add any trailing implicit tracks.
   if (serializeImplicit) {
     for (uint32_t i = numLeadingImplicitTracks + numExplicitTracks;
          i < numSizes; ++i) {
-      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-      val->SetAppUnits(trackSizes[i]);
-      valueList->AppendCSSValue(val.forget());
+      valueList->AppendCSSValue(AppUnitsToCSSValue(trackSizes[i]));
     }
   }
 
@@ -1787,15 +1792,9 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::DoGetPaddingRight() {
 already_AddRefed<CSSValue> nsComputedDOMStyle::DoGetBorderSpacing() {
   RefPtr<nsDOMCSSValueList> valueList = GetROCSSValueList(false);
 
-  RefPtr<nsROCSSPrimitiveValue> xSpacing = new nsROCSSPrimitiveValue;
-  RefPtr<nsROCSSPrimitiveValue> ySpacing = new nsROCSSPrimitiveValue;
-
   const nsStyleTableBorder* border = StyleTableBorder();
-  xSpacing->SetAppUnits(border->mBorderSpacingCol);
-  ySpacing->SetAppUnits(border->mBorderSpacingRow);
-
-  valueList->AppendCSSValue(xSpacing.forget());
-  valueList->AppendCSSValue(ySpacing.forget());
+  valueList->AppendCSSValue(AppUnitsToCSSValue(border->mBorderSpacingCol));
+  valueList->AppendCSSValue(AppUnitsToCSSValue(border->mBorderSpacingRow));
 
   return valueList.forget();
 }
@@ -1833,32 +1832,26 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::DoGetMarginRight() {
 }
 
 already_AddRefed<CSSValue> nsComputedDOMStyle::DoGetHeight() {
-  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
   if (mInnerFrame && !IsNonReplacedInline(mInnerFrame)) {
     AssertFlushedPendingReflows();
-    nsMargin adjustedValues = GetAdjustedValuesForBoxSizing();
-    val->SetAppUnits(mInnerFrame->GetContentRect().height +
-                     adjustedValues.TopBottom());
-  } else {
-    SetValueToSize(val, StylePosition()->mHeight);
+    const nsMargin adjustedValues = GetAdjustedValuesForBoxSizing();
+    return AppUnitsToCSSValue(mInnerFrame->GetContentRect().height +
+                              adjustedValues.TopBottom());
   }
-
+  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
+  SetValueToSize(val, StylePosition()->mHeight);
   return val.forget();
 }
 
 already_AddRefed<CSSValue> nsComputedDOMStyle::DoGetWidth() {
-  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
   if (mInnerFrame && !IsNonReplacedInline(mInnerFrame)) {
     AssertFlushedPendingReflows();
     nsMargin adjustedValues = GetAdjustedValuesForBoxSizing();
-    val->SetAppUnits(mInnerFrame->GetContentRect().width +
-                     adjustedValues.LeftRight());
-  } else {
-    SetValueToSize(val, StylePosition()->mWidth);
+    return AppUnitsToCSSValue(mInnerFrame->GetContentRect().width +
+                              adjustedValues.LeftRight());
   }
-
+  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
+  SetValueToSize(val, StylePosition()->mWidth);
   return val.forget();
 }
 
@@ -1968,14 +1961,13 @@ static_assert(eSideTop == 0 && eSideRight == 1 && eSideBottom == 2 &&
 already_AddRefed<CSSValue> nsComputedDOMStyle::GetNonStaticPositionOffset(
     mozilla::Side aSide, bool aResolveAuto, PercentageBaseGetter aWidthGetter,
     PercentageBaseGetter aHeightGetter) {
-  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
   const nsStylePosition* positionData = StylePosition();
   int32_t sign = 1;
   LengthPercentageOrAuto coord = positionData->mOffset.Get(aSide);
 
   if (coord.IsAuto()) {
     if (!aResolveAuto) {
+      RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
       val->SetString("auto");
       return val.forget();
     }
@@ -1983,14 +1975,12 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetNonStaticPositionOffset(
     sign = -1;
   }
   if (!coord.IsLengthPercentage()) {
-    val->SetPixels(0.0f);
-    return val.forget();
+    return PixelsToCSSValue(0.0f);
   }
 
-  auto& lp = coord.AsLengthPercentage();
+  const auto& lp = coord.AsLengthPercentage();
   if (lp.ConvertsToLength()) {
-    val->SetPixels(sign * lp.ToLengthInCSSPixels());
-    return val.forget();
+    return PixelsToCSSValue(sign * lp.ToLengthInCSSPixels());
   }
 
   PercentageBaseGetter baseGetter = (aSide == eSideLeft || aSide == eSideRight)
@@ -1998,12 +1988,10 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetNonStaticPositionOffset(
                                         : aHeightGetter;
   nscoord percentageBase;
   if (!(this->*baseGetter)(percentageBase)) {
-    val->SetPixels(0.0f);
-    return val.forget();
+    return PixelsToCSSValue(0.0f);
   }
   nscoord result = lp.Resolve(percentageBase);
-  val->SetAppUnits(sign * result);
-  return val.forget();
+  return AppUnitsToCSSValue(sign * result);
 }
 
 already_AddRefed<CSSValue> nsComputedDOMStyle::GetAbsoluteOffset(
@@ -2013,9 +2001,7 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetAbsoluteOffset(
   const auto& oppositeCoord = offset.Get(NS_OPPOSITE_SIDE(aSide));
 
   if (coord.IsAuto() || oppositeCoord.IsAuto()) {
-    RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-    val->SetAppUnits(GetUsedAbsoluteOffset(aSide));
-    return val.forget();
+    return AppUnitsToCSSValue(GetUsedAbsoluteOffset(aSide));
   }
 
   return GetNonStaticPositionOffset(
@@ -2096,23 +2082,18 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetStaticOffset(
 
 already_AddRefed<CSSValue> nsComputedDOMStyle::GetPaddingWidthFor(
     mozilla::Side aSide) {
-  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
-  auto& padding = StylePadding()->mPadding.Get(aSide);
+  const auto& padding = StylePadding()->mPadding.Get(aSide);
   if (!mInnerFrame || !PaddingNeedsUsedValue(padding, *mComputedStyle)) {
+    RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
     SetValueToLengthPercentage(val, padding, true);
-  } else {
-    AssertFlushedPendingReflows();
-    val->SetAppUnits(mInnerFrame->GetUsedPadding().Side(aSide));
+    return val.forget();
   }
-
-  return val.forget();
+  AssertFlushedPendingReflows();
+  return AppUnitsToCSSValue(mInnerFrame->GetUsedPadding().Side(aSide));
 }
 
 already_AddRefed<CSSValue> nsComputedDOMStyle::GetBorderWidthFor(
     mozilla::Side aSide) {
-  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
   nscoord width;
   if (mInnerFrame && mComputedStyle->StyleDisplay()->HasAppearance()) {
     AssertFlushedPendingReflows();
@@ -2120,29 +2101,23 @@ already_AddRefed<CSSValue> nsComputedDOMStyle::GetBorderWidthFor(
   } else {
     width = StyleBorder()->GetComputedBorderWidth(aSide);
   }
-  val->SetAppUnits(width);
-
-  return val.forget();
+  return AppUnitsToCSSValue(width);
 }
 
 already_AddRefed<CSSValue> nsComputedDOMStyle::GetMarginFor(Side aSide) {
-  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-
-  auto& margin = StyleMargin()->mMargin.Get(aSide);
+  const auto& margin = StyleMargin()->mMargin.Get(aSide);
   if (!mInnerFrame || margin.ConvertsToLength()) {
+    RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
     SetValueToLengthPercentageOrAuto(val, margin, false);
-  } else {
-    AssertFlushedPendingReflows();
-
-    // For tables, GetUsedMargin always returns an empty margin, so we
-    // should read the margin from the table wrapper frame instead.
-    val->SetAppUnits(mOuterFrame->GetUsedMargin().Side(aSide));
-    NS_ASSERTION(mOuterFrame == mInnerFrame ||
-                     mInnerFrame->GetUsedMargin() == nsMargin(0, 0, 0, 0),
-                 "Inner tables must have zero margins");
+    return val.forget();
   }
-
-  return val.forget();
+  AssertFlushedPendingReflows();
+  // For tables, GetUsedMargin always returns an empty margin, so we
+  // should read the margin from the table wrapper frame instead.
+  NS_ASSERTION(
+      mOuterFrame == mInnerFrame || mInnerFrame->GetUsedMargin() == nsMargin(),
+      "Inner tables must have zero margins");
+  return AppUnitsToCSSValue(mOuterFrame->GetUsedMargin().Side(aSide));
 }
 
 static void SetValueToExtremumLength(nsROCSSPrimitiveValue* aValue,
@@ -2223,7 +2198,7 @@ void nsComputedDOMStyle::SetValueToLengthPercentage(
     if (aClampNegativeCalc) {
       length = std::max(float(length), 0.0f);
     }
-    return aValue->SetPixels(length);
+    return SetValueToPixels(aValue, length);
   }
   if (aLength.ConvertsToPercentage()) {
     float result = aLength.ToPercentage();
diff --git a/layout/style/nsComputedDOMStyle.h b/layout/style/nsComputedDOMStyle.h
index 4f135a3aca..d1f3458030 100644
--- a/layout/style/nsComputedDOMStyle.h
+++ b/layout/style/nsComputedDOMStyle.h
@@ -148,6 +148,10 @@ class nsComputedDOMStyle final : public nsDOMCSSDeclaration,
   NS_DECL_NSIMUTATIONOBSERVER_PARENTCHAINCHANGED
 
  private:
+  already_AddRefed<nsROCSSPrimitiveValue> AppUnitsToCSSValue(nscoord);
+  already_AddRefed<nsROCSSPrimitiveValue> PixelsToCSSValue(float);
+  void SetValueToPixels(nsROCSSPrimitiveValue*, float);
+
   void GetPropertyValue(const nsCSSPropertyID aPropID,
                         const nsACString& aMaybeCustomPropertyNme,
                         nsACString& aValue);
diff --git a/layout/style/nsMediaFeatures.cpp b/layout/style/nsMediaFeatures.cpp
index f888c127d4..fbdde4102d 100644
--- a/layout/style/nsMediaFeatures.cpp
+++ b/layout/style/nsMediaFeatures.cpp
@@ -336,18 +336,20 @@ StyleDynamicRange Gecko_MediaFeatures_DynamicRange(const Document* aDocument) {
 
 StyleDynamicRange Gecko_MediaFeatures_VideoDynamicRange(
     const Document* aDocument) {
-  if (aDocument->ShouldResistFingerprinting(RFPTarget::CSSVideoDynamicRange)) {
+  if (aDocument->ShouldResistFingerprinting(RFPTarget::CSSVideoDynamicRange) ||
+      !StaticPrefs::layout_css_video_dynamic_range_allows_high()) {
     return StyleDynamicRange::Standard;
   }
   // video-dynamic-range: high has 3 requirements:
   // 1) high peak brightness
   // 2) high contrast ratio
   // 3) color depth > 24
-  // We check the color depth requirement before asking the LookAndFeel
-  // if it is HDR capable.
+
+  // As a proxy for those requirements, return 'High' if the screen associated
+  // with the device context claims to be HDR capable.
   if (nsDeviceContext* dx = GetDeviceContextFor(aDocument)) {
-    if (dx->GetDepth() > 24 &&
-        LookAndFeel::GetInt(LookAndFeel::IntID::VideoDynamicRange)) {
+    if (dx->GetScreenIsHDR()) {
+      // bjw
       return StyleDynamicRange::High;
     }
   }
diff --git a/layout/style/nsROCSSPrimitiveValue.cpp b/layout/style/nsROCSSPrimitiveValue.cpp
index 84911d209b..3b31a14dd2 100644
--- a/layout/style/nsROCSSPrimitiveValue.cpp
+++ b/layout/style/nsROCSSPrimitiveValue.cpp
@@ -102,20 +102,12 @@ void nsROCSSPrimitiveValue::SetDegree(float aValue) {
   mType = CSS_DEG;
 }
 
-void nsROCSSPrimitiveValue::SetAppUnits(nscoord aValue) {
-  SetPixels(nsPresContext::AppUnitsToFloatCSSPixels(aValue));
-}
-
 void nsROCSSPrimitiveValue::SetPixels(float aValue) {
   Reset();
   mValue.mFloat = aValue;
   mType = CSS_PX;
 }
 
-void nsROCSSPrimitiveValue::SetAppUnits(float aValue) {
-  SetAppUnits(NSToCoordRound(aValue));
-}
-
 void nsROCSSPrimitiveValue::SetString(const nsACString& aString) {
   Reset();
   mValue.mString = ToNewUnicode(aString, mozilla::fallible);
diff --git a/layout/style/nsROCSSPrimitiveValue.h b/layout/style/nsROCSSPrimitiveValue.h
index d782a23469..79e6fd6a10 100644
--- a/layout/style/nsROCSSPrimitiveValue.h
+++ b/layout/style/nsROCSSPrimitiveValue.h
@@ -48,8 +48,6 @@ class nsROCSSPrimitiveValue final : public mozilla::dom::CSSValue {
   void SetPercent(float aValue);
   void SetDegree(float aValue);
   void SetPixels(float aValue);
-  void SetAppUnits(nscoord aValue);
-  void SetAppUnits(float aValue);
   void SetString(const nsACString& aString);
   void SetString(const nsAString& aString);
 
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 39f5b1a760..e46566d471 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -3536,7 +3536,7 @@ static nscoord Resolve(const StyleContainIntrinsicSize& aSize,
   }
   MOZ_ASSERT(aSize.HasAuto());
   if (const auto* element = Element::FromNodeOrNull(aFrame.GetContent())) {
-    Maybe<float> lastSize = aAxis == eLogicalAxisBlock
+    Maybe<float> lastSize = aAxis == LogicalAxis::Block
                                 ? element->GetLastRememberedBSize()
                                 : element->GetLastRememberedISize();
     if (lastSize && aFrame.HidesContent()) {
@@ -3556,7 +3556,7 @@ Maybe<nscoord> ContainSizeAxes::ContainIntrinsicBSize(
   }
   const StyleContainIntrinsicSize& bSize =
       aFrame.StylePosition()->ContainIntrinsicBSize(aFrame.GetWritingMode());
-  return Some(Resolve(bSize, aNoneValue, aFrame, eLogicalAxisBlock));
+  return Some(Resolve(bSize, aNoneValue, aFrame, LogicalAxis::Block));
 }
 
 Maybe<nscoord> ContainSizeAxes::ContainIntrinsicISize(
@@ -3566,7 +3566,7 @@ Maybe<nscoord> ContainSizeAxes::ContainIntrinsicISize(
   }
   const StyleContainIntrinsicSize& iSize =
       aFrame.StylePosition()->ContainIntrinsicISize(aFrame.GetWritingMode());
-  return Some(Resolve(iSize, aNoneValue, aFrame, eLogicalAxisInline));
+  return Some(Resolve(iSize, aNoneValue, aFrame, LogicalAxis::Inline));
 }
 
 nsSize ContainSizeAxes::ContainSize(const nsSize& aUncontainedSize,
diff --git a/layout/style/res/forms.css b/layout/style/res/forms.css
index 587534e9f3..044d460ad4 100644
--- a/layout/style/res/forms.css
+++ b/layout/style/res/forms.css
@@ -73,6 +73,8 @@ fieldset {
 
 label {
   cursor: default;
+  /* If you add declarations here, consider whether the select > label and file
+   * input label need them as well. */
 }
 
 /* Default inputs, text inputs, and selects */
@@ -281,6 +283,7 @@ select > button {
 select > label {
   display: inline-block;
   overflow: clip;
+  cursor: unset;
 }
 
 option[label]::before {
@@ -627,6 +630,7 @@ input[type=file] > label {
   min-inline-size: 12em;
   text-align: match-parent;
 
+  cursor: unset;
   color: unset;
   font-size: unset;
   letter-spacing: unset;
diff --git a/layout/style/res/html.css b/layout/style/res/html.css
index ff58ecd4d1..18dd1c4855 100644
--- a/layout/style/res/html.css
+++ b/layout/style/res/html.css
@@ -765,7 +765,7 @@ video > .caption-box {
  * The pseudo element won't inherit CSS styles from its direct parent, `::cue`
  * would actually inherit styles from video because it's video's pseudo element.
  * Therefore, we have to explicitly set some styles which are already defined
- * in its parent element in vtt.jsm.
+ * in its parent element in vtt.sys.mjs.
  */
 ::cue {
   color: rgba(255, 255, 255, 1);
@@ -816,15 +816,21 @@ dialog::backdrop {
   background: rgba(0, 0, 0, 0.1);
 }
 
+/* https://html.spec.whatwg.org/#the-marquee-element-2 */
 marquee {
-  inline-size: -moz-available;
   display: inline-block;
+  text-align: initial;
+  overflow: hidden !important;
+
+  /* See https://github.com/whatwg/html/issues/10249 */
+  inline-size: -moz-available;
   vertical-align: text-bottom;
-  text-align: start;
+  white-space: nowrap;
 }
 
 marquee:is([direction="up"], [direction="down"]) {
   block-size: 200px;
+  white-space: unset;
 }
 
 /* Ruby */
diff --git a/layout/style/test/chrome/chrome-only-media-queries.js b/layout/style/test/chrome/chrome-only-media-queries.js
index aaf313a526..d17976149b 100644
--- a/layout/style/test/chrome/chrome-only-media-queries.js
+++ b/layout/style/test/chrome/chrome-only-media-queries.js
@@ -31,4 +31,5 @@ const CHROME_ONLY_QUERIES = [
   "(-moz-gtk-theme-family: adwaita)",
   "(-moz-gtk-theme-family: breeze)",
   "(-moz-gtk-theme-family: yaru)",
+  "(forced-colors: requested)",
 ];
diff --git a/layout/style/test/mochitest.toml b/layout/style/test/mochitest.toml
index 54ad9736f2..cc5f26708f 100644
--- a/layout/style/test/mochitest.toml
+++ b/layout/style/test/mochitest.toml
@@ -6,16 +6,13 @@ prefs = [
   "gfx.font_loader.delay=0",
   "layout.css.container-queries.enabled=true",
   "layout.css.individual-transform.enabled=true",
-  "layout.css.motion-path-ray.enabled=true",
-  "layout.css.motion-path-basic-shapes.enabled=true",
-  "layout.css.motion-path-coord-box.enabled=true",
-  "layout.css.motion-path-offset-position.enabled=true",
   "layout.css.motion-path-url.enabled=true",
   "layout.css.backdrop-filter.enabled=true",
   "layout.css.fit-content-function.enabled=true",
   "layout.css.scroll-driven-animations.enabled=true",
   "layout.css.animation-composition.enabled=true",
   "layout.css.basic-shape-rect.enabled=true",
+  "layout.css.basic-shape-shape.enabled=true",
   "layout.css.basic-shape-xywh.enabled=true",
   "layout.css.transform-box-content-stroke.enabled=true",
   "layout.css.transition-behavior.enabled=true",
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 2e8b4c71a3..c63d65926e 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -1035,6 +1035,36 @@ if (IsCSSPropertyPrefEnabled("layout.css.basic-shape-rect.enabled")) {
   );
 }
 
+var basicShapeShapeValues = [];
+var basicShapeShapeValuesWithFillRule = [];
+if (IsCSSPropertyPrefEnabled("layout.css.basic-shape-shape.enabled")) {
+  basicShapeShapeValuesWithFillRule.push(
+    "shape(evenodd from 0px 0px, line to 10px 10px)",
+    "shape(nonzero from 0px 0px, line to 10px 10px)"
+  );
+
+  basicShapeShapeValues.push(
+    "shape(from 0px 0%, line to 10px 10%)",
+    "shape(from 10px 10px, move by 10px 5px, line by 20px 40%, close)",
+    "shape(from 10px 10px, hline by 10px, vline to 5rem)",
+    "shape(from 10px 10px, vline by 5%, hline to 1vw)",
+    "shape(from 10px 10px, curve to 50px 20px via 10rem 1%)",
+    "shape(from 10px 10px, smooth to 50px 20px via 10rem 1%)",
+    "shape(from 10% 1rem, arc to 50px 1pt of 20% cw large rotate 25deg)"
+  );
+
+  // It's fine to include this for properties which don't support shape(),
+  // e.g. shape-outside, because they must reject these values.
+  basicShapeInvalidValues.push(
+    "shape()",
+    "shape(evenodd, from 0px 0px)",
+    "shape(from 0px 0px line to 10px 10px)",
+    "shape(from 0px 0px)",
+    "shape(close)",
+    "shape(nonzero, close)"
+  );
+}
+
 if (/* mozGradientsEnabled */ true) {
   // Maybe one day :(
   // Extend gradient lists with valid/invalid moz-prefixed expressions:
@@ -6841,6 +6871,130 @@ var gCSSProperties = {
       "left 10px top",
     ],
   },
+  offset: {
+    domProp: "offset",
+    inherited: false,
+    type: CSS_TYPE_TRUE_SHORTHAND,
+    subproperties: [
+      "offset-path",
+      "offset-distance",
+      "offset-rotate",
+      "offset-anchor",
+      "offset-position",
+    ],
+    initial_values: ["none"],
+    other_values: [
+      "none 30deg reverse",
+      "none 50px reverse 30deg",
+      "none calc(10px + 20%) auto",
+      "none reverse",
+      "none / left center",
+      "path('M 0 0 H 1') -200% auto",
+      "path('M 0 0 H 1') -200%",
+      "path('M 0 0 H 1') 50px",
+      "path('M 0 0 H 1') auto",
+      "path('M 0 0 H 1') reverse 30deg 50px",
+      "path('M 0 0 H 1')",
+      "path('m 20 0 h 100') -7rad 8px / auto",
+      "path('m 0 30 v 100') -7rad 8px / left top",
+      "path('m 0 0 h 100') -7rad 8px",
+      "path('M 0 0 H 100') 100px 0deg",
+      "top right / top left",
+      "top right ray(45deg closest-side)",
+      "50% 50% ray(0rad farthest-side)",
+    ],
+    invalid_values: [
+      "100px 0deg path('m 0 0 h 100')",
+      "30deg",
+      "auto 30deg 100px",
+      "auto / none",
+      "none /",
+      "none / 100px 20px 30deg",
+      "path('M 20 30 A 60 70 80') bottom",
+      "path('M 20 30 A 60 70 80') bottom top",
+      "path('M 20 30 A 60 70 80') 100px 200px",
+      "path('M 20 30 A 60 70 80') reverse auto",
+      "path('M 20 30 A 60 70 80') reverse 10px 30deg",
+      "path('M 20 30 A 60 70 80') /",
+    ],
+  },
+  "offset-anchor": {
+    domProp: "offsetAnchor",
+    inherited: false,
+    type: CSS_TYPE_LONGHAND,
+    initial_values: ["auto"],
+    other_values: [
+      "left bottom",
+      "center center",
+      "calc(20% + 10px) center",
+      "right 30em",
+      "10px 20%",
+      "left -10px top -20%",
+      "right 10% bottom 20em",
+    ],
+    invalid_values: ["none", "10deg", "left 10% top"],
+  },
+  "offset-distance": {
+    domProp: "offsetDistance",
+    inherited: false,
+    type: CSS_TYPE_LONGHAND,
+    initial_values: ["0"],
+    other_values: ["10px", "10%", "190%", "-280%", "calc(30px + 40%)"],
+    invalid_values: ["none", "45deg"],
+  },
+  "offset-path": {
+    domProp: "offsetPath",
+    inherited: false,
+    type: CSS_TYPE_LONGHAND,
+    initial_values: ["none"],
+    other_values: [
+      "ray(0deg)",
+      "ray(45deg closest-side)",
+      "ray(0rad farthest-side)",
+      "ray(0.5turn closest-corner contain)",
+      "ray(200grad farthest-corner)",
+      "ray(sides 180deg)",
+      "ray(contain farthest-side 180deg)",
+      "ray(calc(180deg - 45deg) farthest-side)",
+      "ray(0deg at center center)",
+      "ray(at 10% 10% 1rad)",
+    ]
+      .concat(pathValues.other_values)
+      .concat(basicShapeOtherValues)
+      .concat(basicShapeXywhRectValues)
+      .concat(basicShapeShapeValues),
+    invalid_values: [
+      "path('')",
+      "ray(closest-side)",
+      "ray(0deg, closest-side)",
+      "ray(contain 0deg closest-side contain)",
+    ].concat(pathValues.invalid_values),
+  },
+  "offset-position": {
+    domProp: "offsetPosition",
+    inherited: false,
+    type: CSS_TYPE_LONGHAND,
+    initial_values: ["normal"],
+    other_values: [
+      "auto",
+      "left bottom",
+      "center center",
+      "calc(20% + 10px) center",
+      "right 30em",
+      "10px 20%",
+      "left -10px top -20%",
+      "right 10% bottom 20em",
+    ],
+    invalid_values: ["none", "10deg", "left 10% top"],
+  },
+  "offset-rotate": {
+    domProp: "offsetRotate",
+    inherited: false,
+    type: CSS_TYPE_LONGHAND,
+    initial_values: ["auto"],
+    other_values: ["reverse", "0deg", "0rad reverse", "-45deg", "5turn auto"],
+    invalid_values: ["none", "10px", "reverse 0deg reverse", "reverse auto"],
+  },
   opacity: {
     domProp: "opacity",
     inherited: false,
@@ -8827,7 +8981,9 @@ var gCSSProperties = {
       .concat(basicShapeSVGBoxValues)
       .concat(basicShapeOtherValues)
       .concat(basicShapeOtherValuesWithFillRule)
-      .concat(basicShapeXywhRectValues),
+      .concat(basicShapeXywhRectValues)
+      .concat(basicShapeShapeValues)
+      .concat(basicShapeShapeValuesWithFillRule),
     invalid_values: [
       "path(nonzero)",
       "path(abs, 'M 10 10 L 10 10 z')",
@@ -13409,158 +13565,10 @@ gCSSProperties["scrollbar-width"] = {
   invalid_values: ["1px"],
 };
 
-gCSSProperties["offset"] = {
-  domProp: "offset",
-  inherited: false,
-  type: CSS_TYPE_TRUE_SHORTHAND,
-  subproperties: [
-    "offset-path",
-    "offset-distance",
-    "offset-rotate",
-    "offset-anchor",
-  ],
-  initial_values: ["none"],
-  other_values: [
-    "none 30deg reverse",
-    "none 50px reverse 30deg",
-    "none calc(10px + 20%) auto",
-    "none reverse",
-    "none / left center",
-    "path('M 0 0 H 1') -200% auto",
-    "path('M 0 0 H 1') -200%",
-    "path('M 0 0 H 1') 50px",
-    "path('M 0 0 H 1') auto",
-    "path('M 0 0 H 1') reverse 30deg 50px",
-    "path('M 0 0 H 1')",
-    "path('m 20 0 h 100') -7rad 8px / auto",
-    "path('m 0 30 v 100') -7rad 8px / left top",
-    "path('m 0 0 h 100') -7rad 8px",
-    "path('M 0 0 H 100') 100px 0deg",
-  ],
-  invalid_values: [
-    "100px 0deg path('m 0 0 h 100')",
-    "30deg",
-    "auto 30deg 100px",
-    "auto / none",
-    "none /",
-    "none / 100px 20px 30deg",
-    "path('M 20 30 A 60 70 80') bottom",
-    "path('M 20 30 A 60 70 80') bottom top",
-    "path('M 20 30 A 60 70 80') 100px 200px",
-    "path('M 20 30 A 60 70 80') reverse auto",
-    "path('M 20 30 A 60 70 80') reverse 10px 30deg",
-    "path('M 20 30 A 60 70 80') /",
-  ],
-};
-
-gCSSProperties["offset-path"] = {
-  domProp: "offsetPath",
-  inherited: false,
-  type: CSS_TYPE_LONGHAND,
-  initial_values: ["none"],
-  other_values: [...pathValues.other_values],
-  invalid_values: ["path('')"].concat(pathValues.invalid_values),
-};
-
-if (IsCSSPropertyPrefEnabled("layout.css.motion-path-ray.enabled")) {
-  gCSSProperties["offset-path"]["other_values"].push(
-    "ray(0deg)",
-    "ray(45deg closest-side)",
-    "ray(0rad farthest-side)",
-    "ray(0.5turn closest-corner contain)",
-    "ray(200grad farthest-corner)",
-    "ray(sides 180deg)",
-    "ray(contain farthest-side 180deg)",
-    "ray(calc(180deg - 45deg) farthest-side)",
-    "ray(0deg at center center)",
-    "ray(at 10% 10% 1rad)"
-  );
-
-  gCSSProperties["offset-path"]["invalid_values"].push(
-    "ray(closest-side)",
-    "ray(0deg, closest-side)",
-    "ray(contain 0deg closest-side contain)"
-  );
-}
-
-if (IsCSSPropertyPrefEnabled("layout.css.motion-path-basic-shapes.enabled")) {
-  gCSSProperties["offset-path"]["other_values"].push(
-    ...basicShapeOtherValues,
-    ...basicShapeXywhRectValues
-  );
-}
-
 if (IsCSSPropertyPrefEnabled("layout.css.motion-path-url.enabled")) {
   gCSSProperties["offset-path"]["other_values"].push("url(#svgPath)");
 }
 
-gCSSProperties["offset-distance"] = {
-  domProp: "offsetDistance",
-  inherited: false,
-  type: CSS_TYPE_LONGHAND,
-  initial_values: ["0"],
-  other_values: ["10px", "10%", "190%", "-280%", "calc(30px + 40%)"],
-  invalid_values: ["none", "45deg"],
-};
-
-gCSSProperties["offset-rotate"] = {
-  domProp: "offsetRotate",
-  inherited: false,
-  type: CSS_TYPE_LONGHAND,
-  initial_values: ["auto"],
-  other_values: ["reverse", "0deg", "0rad reverse", "-45deg", "5turn auto"],
-  invalid_values: ["none", "10px", "reverse 0deg reverse", "reverse auto"],
-};
-
-gCSSProperties["offset-anchor"] = {
-  domProp: "offsetAnchor",
-  inherited: false,
-  type: CSS_TYPE_LONGHAND,
-  initial_values: ["auto"],
-  other_values: [
-    "left bottom",
-    "center center",
-    "calc(20% + 10px) center",
-    "right 30em",
-    "10px 20%",
-    "left -10px top -20%",
-    "right 10% bottom 20em",
-  ],
-  invalid_values: ["none", "10deg", "left 10% top"],
-};
-
-if (
-  IsCSSPropertyPrefEnabled("layout.css.motion-path-offset-position.enabled")
-) {
-  gCSSProperties["offset"]["subproperties"].push("offset-position");
-  gCSSProperties["offset"]["other_values"].push("top right / top left");
-
-  if (IsCSSPropertyPrefEnabled("layout.css.motion-path-ray.enabled")) {
-    gCSSProperties["offset"]["other_values"].push(
-      "top right ray(45deg closest-side)",
-      "50% 50% ray(0rad farthest-side)"
-    );
-  }
-
-  gCSSProperties["offset-position"] = {
-    domProp: "offsetPosition",
-    inherited: false,
-    type: CSS_TYPE_LONGHAND,
-    initial_values: ["normal"],
-    other_values: [
-      "auto",
-      "left bottom",
-      "center center",
-      "calc(20% + 10px) center",
-      "right 30em",
-      "10px 20%",
-      "left -10px top -20%",
-      "right 10% bottom 20em",
-    ],
-    invalid_values: ["none", "10deg", "left 10% top"],
-  };
-}
-
 {
   let linear_function_other_values = [
     "linear(0, 1)",
diff --git a/layout/style/test/test_hover_quirk.html b/layout/style/test/test_hover_quirk.html
index 61e19f2a60..7a78185178 100644
--- a/layout/style/test/test_hover_quirk.html
+++ b/layout/style/test/test_hover_quirk.html
@@ -54,6 +54,18 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=783213
     #dynamic-test:hover > * {
       background: rgb(0, 255, 0);
     }
+
+    #dynamic-test-2 :is(button,input,a){
+      background-color:yellow !important;
+    }
+
+    #dynamic-test-2 :is(button,input,a):hover{
+      background-color:lime !important;
+    }
+
+    #dynamic-test-2 :is(button,input):focus{
+      background-color:skyblue !important;
+    }
   </style>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
   <script src="/tests/SimpleTest/EventUtils.js"></script>
@@ -97,6 +109,21 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=783213
       is(getComputedStyle(document.getElementById('should-be-green-on-hover')).backgroundColor,
          "rgb(0, 255, 0)",
          "Dynamic change should invalidate properly");
+
+      synthesizeMouseAtCenter(document.getElementById('button'), {type: "mousemove"});
+      is(getComputedStyle(document.getElementById('button')).backgroundColor,
+        "rgb(0, 255, 0)",
+        "Button hover should be green");
+
+      synthesizeMouseAtCenter(document.getElementById('input'), {type: "mousemove"});
+      is(getComputedStyle(document.getElementById('input')).backgroundColor,
+        "rgb(0, 255, 0)",
+        "Input hover should be green");
+
+      synthesizeMouseAtCenter(document.getElementById('link-2'), {type: "mousemove"});
+      is(getComputedStyle(document.getElementById('link-2')).backgroundColor,
+        "rgb(0, 255, 0)",
+        "Link hover should be green");
       SimpleTest.finish();
     });
   </script>
@@ -113,6 +140,11 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=783213
     <a id="link" href="#">Link<span class="child"></span></a><br>
     <div id="div" class="parent">Div <span><span class="child"></span></span></div><br>
   </div>
+  <div id="dynamic-test-2">
+    <button id="button">Button</button>
+    <input id="input" value="Input">
+    <a id="link-2"href="">Link</a>
+  </div>
   <pre id="test"></pre>
 </body>
 </html>
diff --git a/layout/style/test/test_non_content_accessible_pseudos.html b/layout/style/test/test_non_content_accessible_pseudos.html
index 81493b1a4a..5f2d15d6a2 100644
--- a/layout/style/test/test_non_content_accessible_pseudos.html
+++ b/layout/style/test/test_non_content_accessible_pseudos.html
@@ -30,7 +30,6 @@ const NON_CONTENT_ACCESIBLE_PSEUDOS = [
   ":-moz-dir-attr-rtl",
   ":-moz-dir-attr-like-auto",
   ":-moz-autofill-preview",
-  ":-moz-lwtheme",
   ":-moz-is-html",
   ":-moz-locale-dir(rtl)",
   ":-moz-locale-dir(ltr)",
diff --git a/layout/style/test/test_selectors.html b/layout/style/test/test_selectors.html
index d688139d3c..684e9d6524 100644
--- a/layout/style/test/test_selectors.html
+++ b/layout/style/test/test_selectors.html
@@ -1077,7 +1077,6 @@ function runTests() {
     test_balanced_unparseable(":dir");
 
     // Test chrome-only -moz-lwtheme
-    test_balanced_unparseable(":-moz-lwtheme");
     test_balanced_unparseable(":-moz-broken");
 
     test_balanced_unparseable(":-moz-tree-row(selected)");
diff --git a/layout/style/test/test_style_struct_copy_constructors.html b/layout/style/test/test_style_struct_copy_constructors.html
index 95f727a58d..bce5a4e32c 100644
--- a/layout/style/test/test_style_struct_copy_constructors.html
+++ b/layout/style/test/test_style_struct_copy_constructors.html
@@ -64,6 +64,12 @@ for (var prop in gCSSProperties) {
 }
 
 /** Test using inheritance **/
+
+// TODO(bug 1887221): Zoom right now doesn't apply to explicitly inherited
+// values, so remove it to get consistent results.
+gRule1.style.removeProperty("zoom");
+gRule2.style.removeProperty("zoom");
+
 for (var prop in gCSSProperties) {
   var info = gCSSProperties[prop];
   if (info.inherited && !("subproperties" in info)) {
@@ -79,14 +85,6 @@ for (var prop in gCSSProperties) {
   }
 }
 
-for (var prop in gCSSProperties) {
-  var info = gCSSProperties[prop];
-  if (!("subproperties" in info)) {
-    gRule1.style.removeProperty(prop);
-    gRule2.style.removeProperty(prop);
-  }
-}
-
 </script>
 </pre>
 </body>
diff --git a/layout/svg/CSSClipPathInstance.cpp b/layout/svg/CSSClipPathInstance.cpp
index 77bde2bb54..a8e0306d3e 100644
--- a/layout/svg/CSSClipPathInstance.cpp
+++ b/layout/svg/CSSClipPathInstance.cpp
@@ -66,7 +66,7 @@ bool CSSClipPathInstance::HitTestBasicShapeOrPathClip(nsIFrame* aFrame,
   RefPtr<Path> path = instance.CreateClipPath(
       drawTarget, SVGUtils::GetCSSPxToDevPxMatrix(aFrame));
   float pixelRatio = float(AppUnitsPerCSSPixel()) /
-                     aFrame->PresContext()->AppUnitsPerDevPixel();
+                     float(aFrame->PresContext()->AppUnitsPerDevPixel());
   return path && path->ContainsPoint(ToPoint(aPoint) * pixelRatio, Matrix());
 }
 
@@ -121,8 +121,10 @@ already_AddRefed<Path> CSSClipPathInstance::CreateClipPath(
       return CreateClipPathPolygon(aDrawTarget, r);
     case StyleBasicShape::Tag::Rect:
       return CreateClipPathInset(aDrawTarget, r);
-    case StyleBasicShape::Tag::Path:
-      return CreateClipPathPath(aDrawTarget, r);
+    case StyleBasicShape::Tag::PathOrShape:
+      return basicShape.AsPathOrShape().IsPath()
+                 ? CreateClipPathPath(aDrawTarget, r)
+                 : CreateClipPathShape(aDrawTarget, r);
     default:
       MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE("Unexpected shape type");
   }
@@ -175,18 +177,41 @@ already_AddRefed<Path> CSSClipPathInstance::CreateClipPathInset(
 
 already_AddRefed<Path> CSSClipPathInstance::CreateClipPathPath(
     DrawTarget* aDrawTarget, const nsRect& aRefBox) {
-  const auto& path = mClipPathStyle.AsShape()._0->AsPath();
+  const auto& path = mClipPathStyle.AsShape()._0->AsPathOrShape().AsPath();
 
   RefPtr<PathBuilder> builder = aDrawTarget->CreatePathBuilder(
       path.fill == StyleFillRule::Nonzero ? FillRule::FILL_WINDING
                                           : FillRule::FILL_EVEN_ODD);
-  nscoord appUnitsPerDevPixel =
+  const nscoord appUnitsPerDevPixel =
       mTargetFrame->PresContext()->AppUnitsPerDevPixel();
-  float scale = float(AppUnitsPerCSSPixel()) / appUnitsPerDevPixel;
-  Point offset = Point(aRefBox.x, aRefBox.y) / appUnitsPerDevPixel;
-
+  const Point offset =
+      LayoutDevicePoint::FromAppUnits(aRefBox.TopLeft(), appUnitsPerDevPixel)
+          .ToUnknownPoint();
+  const float scale = mTargetFrame->Style()->EffectiveZoom().Zoom(
+      float(AppUnitsPerCSSPixel()) / float(appUnitsPerDevPixel));
   return SVGPathData::BuildPath(path.path._0.AsSpan(), builder,
-                                StyleStrokeLinecap::Butt, 0.0, offset, scale);
+                                StyleStrokeLinecap::Butt, 0.0, {}, offset,
+                                scale);
+}
+
+already_AddRefed<Path> CSSClipPathInstance::CreateClipPathShape(
+    DrawTarget* aDrawTarget, const nsRect& aRefBox) {
+  const auto& shape = mClipPathStyle.AsShape()._0->AsPathOrShape().AsShape();
+
+  RefPtr<PathBuilder> builder = aDrawTarget->CreatePathBuilder(
+      shape.fill == StyleFillRule::Nonzero ? FillRule::FILL_WINDING
+                                           : FillRule::FILL_EVEN_ODD);
+  const nscoord appUnitsPerDevPixel =
+      mTargetFrame->PresContext()->AppUnitsPerDevPixel();
+  const CSSSize basis = CSSSize::FromAppUnits(aRefBox.Size());
+  const Point offset =
+      LayoutDevicePoint::FromAppUnits(aRefBox.TopLeft(), appUnitsPerDevPixel)
+          .ToUnknownPoint();
+  const float scale = mTargetFrame->Style()->EffectiveZoom().Zoom(
+      float(AppUnitsPerCSSPixel()) / float(appUnitsPerDevPixel));
+  return SVGPathData::BuildPath(shape.commands.AsSpan(), builder,
+                                StyleStrokeLinecap::Butt, 0.0, basis, offset,
+                                scale);
 }
 
 }  // namespace mozilla
diff --git a/layout/svg/CSSClipPathInstance.h b/layout/svg/CSSClipPathInstance.h
index 2d1e16c62f..2cec8c125f 100644
--- a/layout/svg/CSSClipPathInstance.h
+++ b/layout/svg/CSSClipPathInstance.h
@@ -58,6 +58,9 @@ class MOZ_STACK_CLASS CSSClipPathInstance {
   already_AddRefed<Path> CreateClipPathPath(DrawTarget* aDrawTarget,
                                             const nsRect& aRefBox);
 
+  already_AddRefed<Path> CreateClipPathShape(DrawTarget* aDrawTarget,
+                                             const nsRect& aRefBox);
+
   /**
    * The frame for the element that is currently being clipped.
    */
diff --git a/layout/svg/SVGAFrame.cpp b/layout/svg/SVGAFrame.cpp
index 02ff68d7e7..3d09cdc3f5 100644
--- a/layout/svg/SVGAFrame.cpp
+++ b/layout/svg/SVGAFrame.cpp
@@ -82,20 +82,6 @@ nsresult SVGAFrame::AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
     NotifySVGChanged(TRANSFORM_CHANGED);
   }
 
-  // Currently our SMIL implementation does not modify the DOM attributes. Once
-  // we implement the SVG 2 SMIL behaviour this can be removed
-  // SVGAElement::SetAttr/UnsetAttr's ResetLinkState() call will be sufficient.
-  if (aModType == dom::MutationEvent_Binding::SMIL &&
-      aAttribute == nsGkAtoms::href &&
-      (aNameSpaceID == kNameSpaceID_None ||
-       aNameSpaceID == kNameSpaceID_XLink)) {
-    auto* content = static_cast<dom::SVGAElement*>(GetContent());
-
-    // SMIL may change whether an <a> element is a link, in which case we will
-    // need to update the link state.
-    content->ResetLinkState(true, content->ElementHasHref());
-  }
-
   return NS_OK;
 }
 
diff --git a/layout/svg/SVGContextPaint.cpp b/layout/svg/SVGContextPaint.cpp
index 0d7a610df9..e135ea2db3 100644
--- a/layout/svg/SVGContextPaint.cpp
+++ b/layout/svg/SVGContextPaint.cpp
@@ -80,7 +80,7 @@ bool SVGContextPaint::IsAllowedForImageFromURI(nsIURI* aURI) {
     // Only allowed for extensions that have the
     // internal:svgContextPropertiesAllowed permission (added internally from
     // to Mozilla-owned extensions, see `isMozillaExtension` function
-    // defined in Extension.jsm for the exact criteria).
+    // defined in Extension.sys.mjs for the exact criteria).
     return addonPolicy->HasPermission(
         nsGkAtoms::svgContextPropertiesAllowedPermission);
   }
diff --git a/layout/svg/SVGFEImageFrame.cpp b/layout/svg/SVGFEImageFrame.cpp
index 50fb42cd68..d89ed566f1 100644
--- a/layout/svg/SVGFEImageFrame.cpp
+++ b/layout/svg/SVGFEImageFrame.cpp
@@ -121,24 +121,6 @@ nsresult SVGFEImageFrame::AttributeChanged(int32_t aNameSpaceID,
     SVGObserverUtils::InvalidateRenderingObservers(GetParent());
   }
 
-  // Currently our SMIL implementation does not modify the DOM attributes. Once
-  // we implement the SVG 2 SMIL behaviour this can be removed
-  // SVGFEImageElement::AfterSetAttr's implementation will be sufficient.
-  if (aModType == MutationEvent_Binding::SMIL &&
-      aAttribute == nsGkAtoms::href &&
-      (aNameSpaceID == kNameSpaceID_XLink ||
-       aNameSpaceID == kNameSpaceID_None)) {
-    bool hrefIsSet =
-        element->mStringAttributes[SVGFEImageElement::HREF].IsExplicitlySet() ||
-        element->mStringAttributes[SVGFEImageElement::XLINK_HREF]
-            .IsExplicitlySet();
-    if (hrefIsSet) {
-      element->LoadSVGImage(true, true);
-    } else {
-      element->CancelImageRequests(true);
-    }
-  }
-
   return nsIFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
 }
 
diff --git a/layout/svg/SVGGradientFrame.cpp b/layout/svg/SVGGradientFrame.cpp
index 92558cefcd..be6f395cda 100644
--- a/layout/svg/SVGGradientFrame.cpp
+++ b/layout/svg/SVGGradientFrame.cpp
@@ -244,8 +244,10 @@ class MOZ_STACK_CLASS SVGColorStopInterpolator
  public:
   SVGColorStopInterpolator(
       gfxPattern* aGradient, const nsTArray<ColorStop>& aStops,
-      const StyleColorInterpolationMethod& aStyleColorInterpolationMethod)
-      : ColorStopInterpolator(aStops, aStyleColorInterpolationMethod),
+      const StyleColorInterpolationMethod& aStyleColorInterpolationMethod,
+      bool aExtendLastStop)
+      : ColorStopInterpolator(aStops, aStyleColorInterpolationMethod,
+                              aExtendLastStop),
         mGradient(aGradient) {}
 
   void CreateStop(float aPosition, DeviceColor aColor) {
@@ -327,7 +329,8 @@ already_AddRefed<gfxPattern> SVGGradientFrame::GetPaintServerPattern(
   if (StyleSVG()->mColorInterpolation == StyleColorInterpolation::Linearrgb) {
     static constexpr auto interpolationMethod = StyleColorInterpolationMethod{
         StyleColorSpace::SrgbLinear, StyleHueInterpolationMethod::Shorter};
-    SVGColorStopInterpolator interpolator(gradient, stops, interpolationMethod);
+    SVGColorStopInterpolator interpolator(gradient, stops, interpolationMethod,
+                                          false);
     interpolator.CreateStops();
   } else {
     // setup standard sRGB stops
diff --git a/layout/svg/SVGImageFrame.cpp b/layout/svg/SVGImageFrame.cpp
index 242ee6e25e..35693e87c0 100644
--- a/layout/svg/SVGImageFrame.cpp
+++ b/layout/svg/SVGImageFrame.cpp
@@ -191,26 +191,6 @@ nsresult SVGImageFrame::AttributeChanged(int32_t aNameSpaceID,
     }
   }
 
-  // Currently our SMIL implementation does not modify the DOM attributes. Once
-  // we implement the SVG 2 SMIL behaviour this can be removed
-  // SVGImageElement::AfterSetAttr's implementation will be sufficient.
-  if (aModType == MutationEvent_Binding::SMIL &&
-      aAttribute == nsGkAtoms::href &&
-      (aNameSpaceID == kNameSpaceID_XLink ||
-       aNameSpaceID == kNameSpaceID_None)) {
-    SVGImageElement* element = static_cast<SVGImageElement*>(GetContent());
-
-    bool hrefIsSet =
-        element->mStringAttributes[SVGImageElement::HREF].IsExplicitlySet() ||
-        element->mStringAttributes[SVGImageElement::XLINK_HREF]
-            .IsExplicitlySet();
-    if (hrefIsSet) {
-      element->LoadSVGImage(true, true);
-    } else {
-      element->CancelImageRequests(true);
-    }
-  }
-
   return NS_OK;
 }
 
diff --git a/layout/svg/SVGOuterSVGFrame.cpp b/layout/svg/SVGOuterSVGFrame.cpp
index ea0879c0c2..d88327f059 100644
--- a/layout/svg/SVGOuterSVGFrame.cpp
+++ b/layout/svg/SVGOuterSVGFrame.cpp
@@ -126,20 +126,14 @@ NS_QUERYFRAME_TAIL_INHERITING(SVGDisplayContainerFrame)
 
 /* virtual */
 nscoord SVGOuterSVGFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-
   // If this ever changes to return something other than zero, then
   // nsSubDocumentFrame::GetMinISize will also need to change.
-  result = nscoord(0);
-
-  return result;
+  return 0;
 }
 
 /* virtual */
 nscoord SVGOuterSVGFrame::GetPrefISize(gfxContext* aRenderingContext) {
   nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
 
   SVGSVGElement* svg = static_cast<SVGSVGElement*>(GetContent());
   WritingMode wm = GetWritingMode();
@@ -325,7 +319,6 @@ void SVGOuterSVGFrame::Reflow(nsPresContext* aPresContext,
                               nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("SVGOuterSVGFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_FRAME_TRACE(
       NS_FRAME_TRACE_CALLS,
diff --git a/layout/svg/SVGUseFrame.cpp b/layout/svg/SVGUseFrame.cpp
index c655f7b24f..e356895208 100644
--- a/layout/svg/SVGUseFrame.cpp
+++ b/layout/svg/SVGUseFrame.cpp
@@ -42,19 +42,6 @@ void SVGUseFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
   SVGGFrame::Init(aContent, aParent, aPrevInFlow);
 }
 
-nsresult SVGUseFrame::AttributeChanged(int32_t aNamespaceID, nsAtom* aAttribute,
-                                       int32_t aModType) {
-  // Currently our SMIL implementation does not modify the DOM attributes. Once
-  // we implement the SVG 2 SMIL behaviour this can be removed
-  // SVGUseElement::AfterSetAttr's implementation will be sufficient.
-  if (aModType == MutationEvent_Binding::SMIL) {
-    auto* content = SVGUseElement::FromNode(GetContent());
-    content->ProcessAttributeChange(aNamespaceID, aAttribute);
-  }
-
-  return SVGGFrame::AttributeChanged(aNamespaceID, aAttribute, aModType);
-}
-
 void SVGUseFrame::DidSetComputedStyle(ComputedStyle* aOldComputedStyle) {
   SVGGFrame::DidSetComputedStyle(aOldComputedStyle);
 
diff --git a/layout/svg/SVGUseFrame.h b/layout/svg/SVGUseFrame.h
index b72d29247a..a528522991 100644
--- a/layout/svg/SVGUseFrame.h
+++ b/layout/svg/SVGUseFrame.h
@@ -41,8 +41,6 @@ class SVGUseFrame final : public SVGGFrame {
   void DimensionAttributeChanged(bool aHadValidDimensions,
                                  bool aAttributeIsUsed);
 
-  nsresult AttributeChanged(int32_t aNamespaceID, nsAtom* aAttribute,
-                            int32_t aModType) override;
   void DidSetComputedStyle(ComputedStyle* aOldComputedStyle) override;
 
 #ifdef DEBUG_FRAME_DUMP
diff --git a/layout/tables/BasicTableLayoutStrategy.cpp b/layout/tables/BasicTableLayoutStrategy.cpp
index 5cb890c234..b6fe51db59 100644
--- a/layout/tables/BasicTableLayoutStrategy.cpp
+++ b/layout/tables/BasicTableLayoutStrategy.cpp
@@ -37,7 +37,6 @@ BasicTableLayoutStrategy::~BasicTableLayoutStrategy() = default;
 
 /* virtual */
 nscoord BasicTableLayoutStrategy::GetMinISize(gfxContext* aRenderingContext) {
-  DISPLAY_MIN_INLINE_SIZE(mTableFrame, mMinISize);
   if (mMinISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
     ComputeIntrinsicISizes(aRenderingContext);
   }
@@ -47,7 +46,6 @@ nscoord BasicTableLayoutStrategy::GetMinISize(gfxContext* aRenderingContext) {
 /* virtual */
 nscoord BasicTableLayoutStrategy::GetPrefISize(gfxContext* aRenderingContext,
                                                bool aComputingSize) {
-  DISPLAY_PREF_INLINE_SIZE(mTableFrame, mPrefISize);
   NS_ASSERTION((mPrefISize == NS_INTRINSIC_ISIZE_UNKNOWN) ==
                    (mPrefISizePctExpand == NS_INTRINSIC_ISIZE_UNKNOWN),
                "dirtyness out of sync");
@@ -97,18 +95,10 @@ static CellISizeInfo GetISizeInfo(gfxContext* aRenderingContext,
 
     // XXX Should we ignore percentage padding?
     nsIFrame::IntrinsicSizeOffsetData offsets = aFrame->IntrinsicISizeOffsets();
-
-    // In quirks mode, table cell isize should be content-box,
-    // but bsize should be border box.
-    // Because of this historic anomaly, we do not use quirk.css.
-    // (We can't specify one value of box-sizing for isize and another
-    // for bsize).
-    // For this reason, we also do not use box-sizing for just one of
-    // them, as this may be confusing.
-    if (isQuirks || stylePos->mBoxSizing == StyleBoxSizing::Content) {
+    if (stylePos->mBoxSizing == StyleBoxSizing::Content) {
       boxSizingToBorderEdge = offsets.padding + offsets.border;
     } else {
-      // StyleBoxSizing::Border and standards-mode
+      // StyleBoxSizing::Border
       minCoord += offsets.padding + offsets.border;
       prefCoord += offsets.padding + offsets.border;
     }
diff --git a/layout/tables/FixedTableLayoutStrategy.cpp b/layout/tables/FixedTableLayoutStrategy.cpp
index 8d74e3ba12..5eda3b001e 100644
--- a/layout/tables/FixedTableLayoutStrategy.cpp
+++ b/layout/tables/FixedTableLayoutStrategy.cpp
@@ -32,7 +32,6 @@ FixedTableLayoutStrategy::~FixedTableLayoutStrategy() = default;
 
 /* virtual */
 nscoord FixedTableLayoutStrategy::GetMinISize(gfxContext* aRenderingContext) {
-  DISPLAY_MIN_INLINE_SIZE(mTableFrame, mMinISize);
   if (mMinISize != NS_INTRINSIC_ISIZE_UNKNOWN) {
     return mMinISize;
   }
@@ -119,9 +118,7 @@ nscoord FixedTableLayoutStrategy::GetPrefISize(gfxContext* aRenderingContext,
   // algorithm to find the narrowest inline size that would hold all of
   // those intrinsic inline sizes), but it wouldn't be compatible with
   // other browsers.
-  nscoord result = nscoord_MAX;
-  DISPLAY_PREF_INLINE_SIZE(mTableFrame, result);
-  return result;
+  return nscoord_MAX;
 }
 
 /* virtual */
diff --git a/layout/tables/celldata.h b/layout/tables/celldata.h
index 681f0e9f28..22cdb4217d 100644
--- a/layout/tables/celldata.h
+++ b/layout/tables/celldata.h
@@ -347,7 +347,7 @@ inline BCData::BCData() {
   SetBStartStart(true);
   SetIStartStart(true);
   mIStartSize = mCornerSubSize = mBStartSize = 0;
-  mCornerSide = mozilla::eLogicalSideBStart;
+  mCornerSide = static_cast<uint8_t>(mozilla::LogicalSide::BStart);
   mCornerBevel = false;
 }
 
@@ -393,7 +393,7 @@ inline BCPixelSize BCData::GetCorner(mozilla::LogicalSide& aOwnerSide,
 inline void BCData::SetCorner(BCPixelSize aSubSize,
                               mozilla::LogicalSide aOwnerSide, bool aBevel) {
   mCornerSubSize = aSubSize;
-  mCornerSide = aOwnerSide;
+  mCornerSide = static_cast<uint8_t>(aOwnerSide);
   mCornerBevel = aBevel;
 }
 
diff --git a/layout/tables/nsCellMap.cpp b/layout/tables/nsCellMap.cpp
index 7c29baa5b0..60496d3ae0 100644
--- a/layout/tables/nsCellMap.cpp
+++ b/layout/tables/nsCellMap.cpp
@@ -678,7 +678,8 @@ void nsTableCellMap::Dump(char* aString) const {
           printf("l=%d%X%d ", int32_t(size), owner, segStart);
         } else {
           size = cd.GetCorner(side, bevel);
-          printf("c=%d%X%d ", int32_t(size), side, bevel);
+          printf("c=%d%hhX%d ", int32_t(size), static_cast<uint8_t>(side),
+                 bevel);
         }
       }
       BCData& cd = mBCInfo->mBEndIEndCorner;
@@ -690,7 +691,7 @@ void nsTableCellMap::Dump(char* aString) const {
         printf("l=%d%X%d ", int32_t(size), owner, segStart);
       } else {
         size = cd.GetCorner(side, bevel);
-        printf("c=%d%X%d ", int32_t(size), side, bevel);
+        printf("c=%d%hhX%d ", int32_t(size), static_cast<uint8_t>(side), bevel);
       }
     }
     printf("\n");
@@ -818,7 +819,7 @@ bool nsTableCellMap::RowHasSpanningCells(int32_t aRowIndex,
   return false;
 }
 
-// FIXME: The only value callers pass for aSide is eLogicalSideBEnd.
+// FIXME: The only value callers pass for aSide is LogicalSide::BEnd.
 // Consider removing support for the other three values.
 void nsTableCellMap::ResetBStartStart(LogicalSide aSide, nsCellMap& aCellMap,
                                       uint32_t aRowGroupStart,
@@ -829,16 +830,16 @@ void nsTableCellMap::ResetBStartStart(LogicalSide aSide, nsCellMap& aCellMap,
   BCData* bcData = nullptr;
 
   switch (aSide) {
-    case eLogicalSideBEnd:
+    case LogicalSide::BEnd:
       aRowIndex++;
       [[fallthrough]];
-    case eLogicalSideBStart:
+    case LogicalSide::BStart:
       cellData = (BCCellData*)aCellMap.GetDataAt(aRowIndex - aRowGroupStart,
                                                  aColIndex);
       if (cellData) {
         bcData = &cellData->mData;
       } else {
-        NS_ASSERTION(aSide == eLogicalSideBEnd, "program error");
+        NS_ASSERTION(aSide == LogicalSide::BEnd, "program error");
         // try the next row group
         nsCellMap* cellMap = aCellMap.GetNextSibling();
         if (cellMap) {
@@ -851,16 +852,16 @@ void nsTableCellMap::ResetBStartStart(LogicalSide aSide, nsCellMap& aCellMap,
         }
       }
       break;
-    case eLogicalSideIEnd:
+    case LogicalSide::IEnd:
       aColIndex++;
       [[fallthrough]];
-    case eLogicalSideIStart:
+    case LogicalSide::IStart:
       cellData = (BCCellData*)aCellMap.GetDataAt(aRowIndex - aRowGroupStart,
                                                  aColIndex);
       if (cellData) {
         bcData = &cellData->mData;
       } else {
-        NS_ASSERTION(aSide == eLogicalSideIEnd, "program error");
+        NS_ASSERTION(aSide == LogicalSide::IEnd, "program error");
         bcData = GetIEndMostBorder(aRowIndex);
       }
       break;
@@ -890,11 +891,11 @@ void nsTableCellMap::SetBCBorderEdge(LogicalSide aSide, nsCellMap& aCellMap,
   bool changed;
 
   switch (aSide) {
-    case eLogicalSideBEnd:
+    case LogicalSide::BEnd:
       rgYPos++;
       yPos++;
       [[fallthrough]];
-    case eLogicalSideBStart:
+    case LogicalSide::BStart:
       lastIndex = xPos + aLength - 1;
       for (xIndex = xPos; xIndex <= lastIndex; xIndex++) {
         changed = aChanged && (xIndex == xPos);
@@ -908,7 +909,7 @@ void nsTableCellMap::SetBCBorderEdge(LogicalSide aSide, nsCellMap& aCellMap,
                                                         false, 0, damageArea);
             if (!cellData) ABORT0();
           } else {
-            NS_ASSERTION(aSide == eLogicalSideBEnd, "program error");
+            NS_ASSERTION(aSide == LogicalSide::BEnd, "program error");
             // try the next non empty row group
             nsCellMap* cellMap = aCellMap.GetNextSibling();
             while (cellMap && (0 == cellMap->GetRowCount())) {
@@ -935,10 +936,10 @@ void nsTableCellMap::SetBCBorderEdge(LogicalSide aSide, nsCellMap& aCellMap,
           NS_ERROR("Cellmap: BStart edge not found");
       }
       break;
-    case eLogicalSideIEnd:
+    case LogicalSide::IEnd:
       xPos++;
       [[fallthrough]];
-    case eLogicalSideIStart:
+    case LogicalSide::IStart:
       // since bStart, bEnd borders were set, there should already be a cellData
       // entry
       lastIndex = rgYPos + aLength - 1;
@@ -948,7 +949,7 @@ void nsTableCellMap::SetBCBorderEdge(LogicalSide aSide, nsCellMap& aCellMap,
         if (cellData) {
           cellData->mData.SetIStartEdge(aOwner, aSize, changed);
         } else {
-          NS_ASSERTION(aSide == eLogicalSideIEnd, "program error");
+          NS_ASSERTION(aSide == LogicalSide::IEnd, "program error");
           BCData* bcData = GetIEndMostBorder(yIndex + aCellMapStart);
           if (bcData) {
             bcData->SetIStartEdge(aOwner, aSize, changed);
@@ -2225,7 +2226,8 @@ void nsCellMap::Dump(bool aIsBorderCollapse) const {
               printf("l=%d%d%d ", int32_t(size), owner, segStart);
             } else {
               size = cd->mData.GetCorner(side, bevel);
-              printf("c=%d%d%d ", int32_t(size), side, bevel);
+              printf("c=%d%hhu%d ", int32_t(size), static_cast<uint8_t>(side),
+                     bevel);
             }
           }
         }
diff --git a/layout/tables/nsTableCellFrame.cpp b/layout/tables/nsTableCellFrame.cpp
index 6eb1c3146a..fdfa5e305e 100644
--- a/layout/tables/nsTableCellFrame.cpp
+++ b/layout/tables/nsTableCellFrame.cpp
@@ -48,9 +48,6 @@ nsTableCellFrame::nsTableCellFrame(ComputedStyle* aStyle,
                                    nsTableFrame* aTableFrame, ClassID aID)
     : nsContainerFrame(aStyle, aTableFrame->PresContext(), aID),
       mDesiredSize(aTableFrame->GetWritingMode()) {
-  mColIndex = 0;
-  mPriorAvailISize = 0;
-
   SetContentEmpty(false);
 }
 
@@ -392,9 +389,14 @@ LogicalSides nsTableCellFrame::GetLogicalSkipSides() const {
 /* virtual */
 nsMargin nsTableCellFrame::GetBorderOverflow() { return nsMargin(0, 0, 0, 0); }
 
-// Align the cell's child frame within the cell
+void nsTableCellFrame::BlockDirAlignChild(
+    WritingMode aWM, nscoord aMaxAscent,
+    ForceAlignTopForTableCell aForceAlignTop) {
+  MOZ_ASSERT(aForceAlignTop != ForceAlignTopForTableCell::Yes ||
+                 PresContext()->IsPaginated(),
+             "We shouldn't force table-cells to do 'vertical-align:top' if "
+             "we're not in printing!");
 
-void nsTableCellFrame::BlockDirAlignChild(WritingMode aWM, nscoord aMaxAscent) {
   /* It's the 'border-collapse' on the table that matters */
   const LogicalMargin border = GetLogicalUsedBorder(GetWritingMode())
                                    .ApplySkipSides(GetLogicalSkipSides())
@@ -413,8 +415,11 @@ void nsTableCellFrame::BlockDirAlignChild(WritingMode aWM, nscoord aMaxAscent) {
   nscoord childBSize = kidRect.BSize(aWM);
 
   // Vertically align the child
+  const auto verticalAlign = aForceAlignTop == ForceAlignTopForTableCell::Yes
+                                 ? StyleVerticalAlignKeyword::Top
+                                 : GetVerticalAlign();
   nscoord kidBStart = 0;
-  switch (GetVerticalAlign()) {
+  switch (verticalAlign) {
     case StyleVerticalAlignKeyword::Baseline:
       if (!GetContentEmpty()) {
         // Align the baselines of the child frame with the baselines of
@@ -590,26 +595,18 @@ nsIScrollableFrame* nsTableCellFrame::GetScrollTargetFrame() const {
 
 /* virtual */
 nscoord nsTableCellFrame::GetMinISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_MIN_INLINE_SIZE(this, result);
-
   nsIFrame* inner = mFrames.FirstChild();
-  result = nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner,
-                                                IntrinsicISizeType::MinISize,
-                                                nsLayoutUtils::IGNORE_PADDING);
-  return result;
+  return nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner,
+                                              IntrinsicISizeType::MinISize,
+                                              nsLayoutUtils::IGNORE_PADDING);
 }
 
 /* virtual */
 nscoord nsTableCellFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord result = 0;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
   nsIFrame* inner = mFrames.FirstChild();
-  result = nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner,
-                                                IntrinsicISizeType::PrefISize,
-                                                nsLayoutUtils::IGNORE_PADDING);
-  return result;
+  return nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner,
+                                              IntrinsicISizeType::PrefISize,
+                                              nsLayoutUtils::IGNORE_PADDING);
 }
 
 /* virtual */ nsIFrame::IntrinsicSizeOffsetData
@@ -675,7 +672,6 @@ void nsTableCellFrame::Reflow(nsPresContext* aPresContext,
                               nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableCellFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   if (aReflowInput.mFlags.mSpecialBSizeReflow) {
@@ -708,14 +704,12 @@ void nsTableCellFrame::Reflow(nsPresContext* aPresContext,
     if (aReflowInput.mFlags.mSpecialBSizeReflow) {
       const_cast<ReflowInput&>(aReflowInput)
           .SetComputedBSize(BSize(wm) - bp.BStartEnd(wm));
-      DISPLAY_REFLOW_CHANGE();
     } else {
       const nscoord computedUnpaginatedBSize =
           CalcUnpaginatedBSize(*this, *tableFrame, bp.BStartEnd(wm));
       if (computedUnpaginatedBSize > 0) {
         const_cast<ReflowInput&>(aReflowInput)
             .SetComputedBSize(computedUnpaginatedBSize);
-        DISPLAY_REFLOW_CHANGE();
       }
     }
   }
@@ -977,11 +971,11 @@ LogicalMargin nsBCTableCellFrame::GetBorderWidth(WritingMode aWM) const {
 
 BCPixelSize nsBCTableCellFrame::GetBorderWidth(LogicalSide aSide) const {
   switch (aSide) {
-    case eLogicalSideBStart:
+    case LogicalSide::BStart:
       return BC_BORDER_END_HALF(mBStartBorder);
-    case eLogicalSideIEnd:
+    case LogicalSide::IEnd:
       return BC_BORDER_START_HALF(mIEndBorder);
-    case eLogicalSideBEnd:
+    case LogicalSide::BEnd:
       return BC_BORDER_START_HALF(mBEndBorder);
     default:
       return BC_BORDER_END_HALF(mIStartBorder);
@@ -990,13 +984,13 @@ BCPixelSize nsBCTableCellFrame::GetBorderWidth(LogicalSide aSide) const {
 
 void nsBCTableCellFrame::SetBorderWidth(LogicalSide aSide, BCPixelSize aValue) {
   switch (aSide) {
-    case eLogicalSideBStart:
+    case LogicalSide::BStart:
       mBStartBorder = aValue;
       break;
-    case eLogicalSideIEnd:
+    case LogicalSide::IEnd:
       mIEndBorder = aValue;
       break;
-    case eLogicalSideBEnd:
+    case LogicalSide::BEnd:
       mBEndBorder = aValue;
       break;
     default:
diff --git a/layout/tables/nsTableCellFrame.h b/layout/tables/nsTableCellFrame.h
index f9b6f3ccac..ae1a881819 100644
--- a/layout/tables/nsTableCellFrame.h
+++ b/layout/tables/nsTableCellFrame.h
@@ -34,9 +34,6 @@ class PresShell;
 class nsTableCellFrame : public nsContainerFrame,
                          public nsITableCellLayout,
                          public nsIPercentBSizeObserver {
-  typedef mozilla::gfx::DrawTarget DrawTarget;
-  typedef mozilla::image::ImgDrawResult ImgDrawResult;
-
   friend nsTableCellFrame* NS_NewTableCellFrame(mozilla::PresShell* aPresShell,
                                                 ComputedStyle* aStyle,
                                                 nsTableFrame* aTableFrame);
@@ -44,11 +41,6 @@ class nsTableCellFrame : public nsContainerFrame,
   nsTableCellFrame(ComputedStyle* aStyle, nsTableFrame* aTableFrame)
       : nsTableCellFrame(aStyle, aTableFrame, kClassID) {}
 
- protected:
-  typedef mozilla::WritingMode WritingMode;
-  typedef mozilla::LogicalSide LogicalSide;
-  typedef mozilla::LogicalMargin LogicalMargin;
-
  public:
   NS_DECL_QUERYFRAME
   NS_DECL_FRAMEARENA_HELPERS(nsTableCellFrame)
@@ -122,7 +114,9 @@ class nsTableCellFrame : public nsContainerFrame,
   nsresult GetFrameName(nsAString& aResult) const override;
 #endif
 
-  void BlockDirAlignChild(mozilla::WritingMode aWM, nscoord aMaxAscent);
+  // Align the cell's child frame within the cell.
+  void BlockDirAlignChild(mozilla::WritingMode aWM, nscoord aMaxAscent,
+                          mozilla::ForceAlignTopForTableCell aForceAlignTop);
 
   /*
    * Get the value of vertical-align adjusted for CSS 2's rules for a
@@ -193,20 +187,24 @@ class nsTableCellFrame : public nsContainerFrame,
 
   void SetColIndex(int32_t aColIndex);
 
-  /** return the available isize given to this frame during its last reflow */
-  inline nscoord GetPriorAvailISize();
-
-  /** set the available isize given to this frame during its last reflow */
-  inline void SetPriorAvailISize(nscoord aPriorAvailISize);
-
-  /** return the desired size returned by this frame during its last reflow */
-  inline mozilla::LogicalSize GetDesiredSize();
+  // Get or set the available isize given to this frame during its last reflow.
+  nscoord GetPriorAvailISize() const { return mPriorAvailISize; }
+  void SetPriorAvailISize(nscoord aPriorAvailISize) {
+    mPriorAvailISize = aPriorAvailISize;
+  }
 
-  /** set the desired size returned by this frame during its last reflow */
-  inline void SetDesiredSize(const ReflowOutput& aDesiredSize);
+  // Get or set the desired size returned by this frame during its last reflow.
+  mozilla::LogicalSize GetDesiredSize() const { return mDesiredSize; }
+  void SetDesiredSize(const ReflowOutput& aDesiredSize) {
+    mDesiredSize = aDesiredSize.Size(GetWritingMode());
+  }
 
-  bool GetContentEmpty() const;
-  void SetContentEmpty(bool aContentEmpty);
+  bool GetContentEmpty() const {
+    return HasAnyStateBits(NS_TABLE_CELL_CONTENT_EMPTY);
+  }
+  void SetContentEmpty(bool aContentEmpty) {
+    AddOrRemoveStateBits(NS_TABLE_CELL_CONTENT_EMPTY, aContentEmpty);
+  }
 
   nsTableCellFrame* GetNextCell() const {
     nsIFrame* sibling = GetNextSibling();
@@ -216,7 +214,7 @@ class nsTableCellFrame : public nsContainerFrame,
     return static_cast<nsTableCellFrame*>(sibling);
   }
 
-  virtual LogicalMargin GetBorderWidth(WritingMode aWM) const;
+  virtual mozilla::LogicalMargin GetBorderWidth(mozilla::WritingMode aWM) const;
 
   void DecorateForSelection(DrawTarget* aDrawTarget, nsPoint aPt);
 
@@ -251,44 +249,17 @@ class nsTableCellFrame : public nsContainerFrame,
 
   friend class nsTableRowFrame;
 
-  uint32_t mColIndex;  // the starting column for this cell
-
-  nscoord mPriorAvailISize;           // the avail isize during the last reflow
-  mozilla::LogicalSize mDesiredSize;  // the last desired inline and block size
-};
-
-inline nscoord nsTableCellFrame::GetPriorAvailISize() {
-  return mPriorAvailISize;
-}
-
-inline void nsTableCellFrame::SetPriorAvailISize(nscoord aPriorAvailISize) {
-  mPriorAvailISize = aPriorAvailISize;
-}
-
-inline mozilla::LogicalSize nsTableCellFrame::GetDesiredSize() {
-  return mDesiredSize;
-}
-
-inline void nsTableCellFrame::SetDesiredSize(const ReflowOutput& aDesiredSize) {
-  mDesiredSize = aDesiredSize.Size(GetWritingMode());
-}
+  // The starting column for this cell
+  uint32_t mColIndex = 0;
 
-inline bool nsTableCellFrame::GetContentEmpty() const {
-  return HasAnyStateBits(NS_TABLE_CELL_CONTENT_EMPTY);
-}
+  // The avail isize during the last reflow
+  nscoord mPriorAvailISize = 0;
 
-inline void nsTableCellFrame::SetContentEmpty(bool aContentEmpty) {
-  if (aContentEmpty) {
-    AddStateBits(NS_TABLE_CELL_CONTENT_EMPTY);
-  } else {
-    RemoveStateBits(NS_TABLE_CELL_CONTENT_EMPTY);
-  }
-}
+  // The last desired inline and block size
+  mozilla::LogicalSize mDesiredSize;
+};
 
-// nsBCTableCellFrame
 class nsBCTableCellFrame final : public nsTableCellFrame {
-  typedef mozilla::image::ImgDrawResult ImgDrawResult;
-
  public:
   NS_DECL_FRAMEARENA_HELPERS(nsBCTableCellFrame)
 
@@ -299,13 +270,14 @@ class nsBCTableCellFrame final : public nsTableCellFrame {
   nsMargin GetUsedBorder() const override;
 
   // Get the *inner half of the border only*, in twips.
-  LogicalMargin GetBorderWidth(WritingMode aWM) const override;
+  mozilla::LogicalMargin GetBorderWidth(
+      mozilla::WritingMode aWM) const override;
 
   // Get the *inner half of the border only*, in pixels.
-  BCPixelSize GetBorderWidth(LogicalSide aSide) const;
+  BCPixelSize GetBorderWidth(mozilla::LogicalSide aSide) const;
 
   // Set the full (both halves) width of the border
-  void SetBorderWidth(LogicalSide aSide, BCPixelSize aPixelValue);
+  void SetBorderWidth(mozilla::LogicalSide aSide, BCPixelSize aPixelValue);
 
   nsMargin GetBorderOverflow() override;
 
diff --git a/layout/tables/nsTableColFrame.cpp b/layout/tables/nsTableColFrame.cpp
index 16eab74cab..8031d4c47c 100644
--- a/layout/tables/nsTableColFrame.cpp
+++ b/layout/tables/nsTableColFrame.cpp
@@ -82,7 +82,6 @@ void nsTableColFrame::Reflow(nsPresContext* aPresContext,
                              nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableColFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   aDesiredSize.ClearSize();
   const nsStyleVisibility* colVis = StyleVisibility();
diff --git a/layout/tables/nsTableColGroupFrame.cpp b/layout/tables/nsTableColGroupFrame.cpp
index 54fe53a5c4..bf0200e27c 100644
--- a/layout/tables/nsTableColGroupFrame.cpp
+++ b/layout/tables/nsTableColGroupFrame.cpp
@@ -329,7 +329,6 @@ void nsTableColGroupFrame::Reflow(nsPresContext* aPresContext,
                                   nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableColGroupFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   NS_ASSERTION(nullptr != mContent, "bad state -- null content for frame");
 
diff --git a/layout/tables/nsTableFrame.cpp b/layout/tables/nsTableFrame.cpp
index e7fd7340bf..84bdbc48af 100644
--- a/layout/tables/nsTableFrame.cpp
+++ b/layout/tables/nsTableFrame.cpp
@@ -1615,7 +1615,6 @@ void nsTableFrame::Reflow(nsPresContext* aPresContext,
                           nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
   MOZ_ASSERT(!HasAnyStateBits(NS_FRAME_OUT_OF_FLOW),
              "The nsTableWrapperFrame should be the out-of-flow if needed");
@@ -4537,7 +4536,7 @@ struct BCCornerInfo {
     ownerColor = 0;
     ownerWidth = subWidth = ownerElem = subSide = subElem = hasDashDot =
         numSegs = bevel = 0;
-    ownerSide = eLogicalSideBStart;
+    ownerSide = static_cast<uint16_t>(LogicalSide::BStart);
     ownerStyle = BORDER_STYLE_UNSET;
     subStyle = StyleBorderStyle::Solid;
   }
@@ -4552,7 +4551,7 @@ struct BCCornerInfo {
                         // border perpendicular to ownerSide
   StyleBorderStyle subStyle;    // border style of subElem
   StyleBorderStyle ownerStyle;  // border style of ownerElem
-  uint16_t ownerSide : 2;  // LogicalSide (e.g eLogicalSideBStart, etc) of the
+  uint16_t ownerSide : 2;  // LogicalSide (e.g LogicalSide::BStart, etc) of the
                            // border owning the corner relative to the corner
   uint16_t
       ownerElem : 4;  // elem type (e.g. eTable, eGroup, etc) owning the corner
@@ -4575,7 +4574,7 @@ void BCCornerInfo::Set(mozilla::LogicalSide aSide, BCCellBorder aBorder) {
   ownerStyle = aBorder.style;
   ownerWidth = aBorder.width;
   ownerColor = aBorder.color;
-  ownerSide = aSide;
+  ownerSide = static_cast<uint16_t>(aSide);
   hasDashDot = 0;
   numSegs = 0;
   if (aBorder.width > 0) {
@@ -4586,7 +4585,8 @@ void BCCornerInfo::Set(mozilla::LogicalSide aSide, BCCellBorder aBorder) {
   bevel = 0;
   subWidth = 0;
   // the following will get set later
-  subSide = IsInline(aSide) ? eLogicalSideBStart : eLogicalSideIStart;
+  subSide = static_cast<uint16_t>(IsInline(aSide) ? LogicalSide::BStart
+                                                  : LogicalSide::IStart);
   subElem = eTableOwner;
   subStyle = StyleBorderStyle::Solid;
 }
@@ -4631,16 +4631,16 @@ void BCCornerInfo::Update(mozilla::LogicalSide aSide, BCCellBorder aBorder) {
         subStyle = tempBorder.style;
         subWidth = tempBorder.width;
         if (!firstWins) {
-          subSide = aSide;
+          subSide = static_cast<uint16_t>(aSide);
         }
       }
     } else {  // input args are dominant
-      ownerSide = aSide;
+      ownerSide = static_cast<uint16_t>(aSide);
       if (::Perpendicular(oldSide, LogicalSide(ownerSide))) {
         subElem = oldBorder.owner;
         subStyle = oldBorder.style;
         subWidth = oldBorder.width;
-        subSide = oldSide;
+        subSide = static_cast<uint16_t>(oldSide);
       }
     }
     if (aBorder.width > 0) {
@@ -4886,8 +4886,8 @@ void BCMapCellInfo::SetIEndBorderWidths(BCPixelSize aWidth) {
   // update the borders of the cells and cols affected
   if (mCell) {
     mCell->SetBorderWidth(
-        eLogicalSideIEnd,
-        std::max(aWidth, mCell->GetBorderWidth(eLogicalSideIEnd)));
+        LogicalSide::IEnd,
+        std::max(aWidth, mCell->GetBorderWidth(LogicalSide::IEnd)));
   }
   if (mEndCol) {
     BCPixelSize half = BC_BORDER_START_HALF(aWidth);
@@ -4899,8 +4899,8 @@ void BCMapCellInfo::SetBEndBorderWidths(BCPixelSize aWidth) {
   // update the borders of the affected cells and rows
   if (mCell) {
     mCell->SetBorderWidth(
-        eLogicalSideBEnd,
-        std::max(aWidth, mCell->GetBorderWidth(eLogicalSideBEnd)));
+        LogicalSide::BEnd,
+        std::max(aWidth, mCell->GetBorderWidth(LogicalSide::BEnd)));
   }
   if (mEndRow) {
     BCPixelSize half = BC_BORDER_START_HALF(aWidth);
@@ -4912,8 +4912,8 @@ void BCMapCellInfo::SetBEndBorderWidths(BCPixelSize aWidth) {
 void BCMapCellInfo::SetBStartBorderWidths(BCPixelSize aWidth) {
   if (mCell) {
     mCell->SetBorderWidth(
-        eLogicalSideBStart,
-        std::max(aWidth, mCell->GetBorderWidth(eLogicalSideBStart)));
+        LogicalSide::BStart,
+        std::max(aWidth, mCell->GetBorderWidth(LogicalSide::BStart)));
   }
   if (mStartRow) {
     BCPixelSize half = BC_BORDER_END_HALF(aWidth);
@@ -4925,8 +4925,8 @@ void BCMapCellInfo::SetBStartBorderWidths(BCPixelSize aWidth) {
 void BCMapCellInfo::SetIStartBorderWidths(BCPixelSize aWidth) {
   if (mCell) {
     mCell->SetBorderWidth(
-        eLogicalSideIStart,
-        std::max(aWidth, mCell->GetBorderWidth(eLogicalSideIStart)));
+        LogicalSide::IStart,
+        std::max(aWidth, mCell->GetBorderWidth(LogicalSide::IStart)));
   }
   if (mStartCol) {
     BCPixelSize half = BC_BORDER_END_HALF(aWidth);
@@ -4957,46 +4957,46 @@ void BCMapCellInfo::IncrementRow(bool aResetToBStartRowOfCell) {
 BCCellBorder BCMapCellInfo::GetBStartEdgeBorder() {
   return CompareBorders(mTableFrame, mCurrentColGroupFrame, mCurrentColFrame,
                         mRowGroup, mStartRow, mCell, mTableWM,
-                        eLogicalSideBStart, !ADJACENT);
+                        LogicalSide::BStart, !ADJACENT);
 }
 
 BCCellBorder BCMapCellInfo::GetBEndEdgeBorder() {
   return CompareBorders(mTableFrame, mCurrentColGroupFrame, mCurrentColFrame,
-                        mRowGroup, mEndRow, mCell, mTableWM, eLogicalSideBEnd,
+                        mRowGroup, mEndRow, mCell, mTableWM, LogicalSide::BEnd,
                         ADJACENT);
 }
 BCCellBorder BCMapCellInfo::GetIStartEdgeBorder() {
   return CompareBorders(mTableFrame, mColGroup, mStartCol, mRowGroup,
-                        mCurrentRowFrame, mCell, mTableWM, eLogicalSideIStart,
+                        mCurrentRowFrame, mCell, mTableWM, LogicalSide::IStart,
                         !ADJACENT);
 }
 BCCellBorder BCMapCellInfo::GetIEndEdgeBorder() {
   return CompareBorders(mTableFrame, mColGroup, mEndCol, mRowGroup,
-                        mCurrentRowFrame, mCell, mTableWM, eLogicalSideIEnd,
+                        mCurrentRowFrame, mCell, mTableWM, LogicalSide::IEnd,
                         ADJACENT);
 }
 BCCellBorder BCMapCellInfo::GetIEndInternalBorder() {
   const nsIFrame* cg = mCgAtEnd ? mColGroup : nullptr;
   return CompareBorders(nullptr, cg, mEndCol, nullptr, nullptr, mCell, mTableWM,
-                        eLogicalSideIEnd, ADJACENT);
+                        LogicalSide::IEnd, ADJACENT);
 }
 
 BCCellBorder BCMapCellInfo::GetIStartInternalBorder() {
   const nsIFrame* cg = mCgAtStart ? mColGroup : nullptr;
   return CompareBorders(nullptr, cg, mStartCol, nullptr, nullptr, mCell,
-                        mTableWM, eLogicalSideIStart, !ADJACENT);
+                        mTableWM, LogicalSide::IStart, !ADJACENT);
 }
 
 BCCellBorder BCMapCellInfo::GetBEndInternalBorder() {
   const nsIFrame* rg = mRgAtEnd ? mRowGroup : nullptr;
   return CompareBorders(nullptr, nullptr, nullptr, rg, mEndRow, mCell, mTableWM,
-                        eLogicalSideBEnd, ADJACENT);
+                        LogicalSide::BEnd, ADJACENT);
 }
 
 BCCellBorder BCMapCellInfo::GetBStartInternalBorder() {
   const nsIFrame* rg = mRgAtStart ? mRowGroup : nullptr;
   return CompareBorders(nullptr, nullptr, nullptr, rg, mStartRow, mCell,
-                        mTableWM, eLogicalSideBStart, !ADJACENT);
+                        mTableWM, LogicalSide::BStart, !ADJACENT);
 }
 
 //  Calculate border information for border-collapsed tables.
@@ -5164,9 +5164,10 @@ void nsTableFrame::CalcBCBorders() {
     // table, row group, row if the border is at the bStart of the table,
     // otherwise it was processed in a previous row
     if (0 == info.mRowIndex) {
-      if (!tableBorderReset[eLogicalSideBStart]) {
+      uint8_t idxBStart = static_cast<uint8_t>(LogicalSide::BStart);
+      if (!tableBorderReset[idxBStart]) {
         propData->mBStartBorderWidth = 0;
-        tableBorderReset[eLogicalSideBStart] = true;
+        tableBorderReset[idxBStart] = true;
       }
       for (int32_t colIdx = info.mColIndex; colIdx <= info.GetCellEndColIndex();
            colIdx++) {
@@ -5175,9 +5176,9 @@ void nsTableFrame::CalcBCBorders() {
         BCCornerInfo& bStartIStartCorner = bStartCorners[colIdx];
         // Mark inline-end direction border from this corner.
         if (0 == colIdx) {
-          bStartIStartCorner.Set(eLogicalSideIEnd, currentBorder);
+          bStartIStartCorner.Set(LogicalSide::IEnd, currentBorder);
         } else {
-          bStartIStartCorner.Update(eLogicalSideIEnd, currentBorder);
+          bStartIStartCorner.Update(LogicalSide::IEnd, currentBorder);
           tableCellMap->SetBCBorderCorner(
               LogicalCorner::BStartIStart, *iter.mCellMap, 0, 0, colIdx,
               LogicalSide(bStartIStartCorner.ownerSide),
@@ -5186,7 +5187,7 @@ void nsTableFrame::CalcBCBorders() {
         // Above, we set the corner `colIndex` column as having a border towards
         // inline-end, heading towards the next column. Vice versa is also true,
         // where the next column has a border heading towards this column.
-        bStartCorners[colIdx + 1].Set(eLogicalSideIStart, currentBorder);
+        bStartCorners[colIdx + 1].Set(LogicalSide::IStart, currentBorder);
         MOZ_ASSERT(firstRowBStartEdgeBorder,
                    "Inline start border tracking not set?");
         // update firstRowBStartEdgeBorder and see if a new segment starts
@@ -5196,7 +5197,7 @@ void nsTableFrame::CalcBCBorders() {
                                      firstRowBStartEdgeBorder.ref())
                 : true;
         // store the border segment in the cell map
-        tableCellMap->SetBCBorderEdge(eLogicalSideBStart, *iter.mCellMap, 0, 0,
+        tableCellMap->SetBCBorderEdge(LogicalSide::BStart, *iter.mCellMap, 0, 0,
                                       colIdx, 1, currentBorder.owner,
                                       currentBorder.width, startSeg);
 
@@ -5225,9 +5226,10 @@ void nsTableFrame::CalcBCBorders() {
     // table, col group, col if the border is at the iStart of the table,
     // otherwise it was processed in a previous col
     if (0 == info.mColIndex) {
-      if (!tableBorderReset[eLogicalSideIStart]) {
+      uint8_t idxIStart = static_cast<uint8_t>(LogicalSide::IStart);
+      if (!tableBorderReset[idxIStart]) {
         propData->mIStartBorderWidth = 0;
-        tableBorderReset[eLogicalSideIStart] = true;
+        tableBorderReset[idxIStart] = true;
       }
       info.mCurrentRowFrame = nullptr;
       for (int32_t rowB = info.mRowIndex; rowB <= info.GetCellEndRowIndex();
@@ -5236,17 +5238,17 @@ void nsTableFrame::CalcBCBorders() {
         BCCellBorder currentBorder = info.GetIStartEdgeBorder();
         BCCornerInfo& bStartIStartCorner =
             (0 == rowB) ? bStartCorners[0] : bEndCorners[0];
-        bStartIStartCorner.Update(eLogicalSideBEnd, currentBorder);
+        bStartIStartCorner.Update(LogicalSide::BEnd, currentBorder);
         tableCellMap->SetBCBorderCorner(
             LogicalCorner::BStartIStart, *iter.mCellMap, iter.mRowGroupStart,
             rowB, 0, LogicalSide(bStartIStartCorner.ownerSide),
             bStartIStartCorner.subWidth, bStartIStartCorner.bevel);
-        bEndCorners[0].Set(eLogicalSideBStart, currentBorder);
+        bEndCorners[0].Set(LogicalSide::BStart, currentBorder);
 
         // update lastBlockDirBorders and see if a new segment starts
         bool startSeg = SetBorder(currentBorder, lastBlockDirBorders[0]);
         // store the border segment in the cell map
-        tableCellMap->SetBCBorderEdge(eLogicalSideIStart, *iter.mCellMap,
+        tableCellMap->SetBCBorderEdge(LogicalSide::IStart, *iter.mCellMap,
                                       iter.mRowGroupStart, rowB, info.mColIndex,
                                       1, currentBorder.owner,
                                       currentBorder.width, startSeg);
@@ -5261,9 +5263,10 @@ void nsTableFrame::CalcBCBorders() {
     // cells and the table, row group, row
     if (info.mNumTableCols == info.GetCellEndColIndex() + 1) {
       // touches iEnd edge of table
-      if (!tableBorderReset[eLogicalSideIEnd]) {
+      uint8_t idxIEnd = static_cast<uint8_t>(LogicalSide::IEnd);
+      if (!tableBorderReset[idxIEnd]) {
         propData->mIEndBorderWidth = 0;
-        tableBorderReset[eLogicalSideIEnd] = true;
+        tableBorderReset[idxIEnd] = true;
       }
       info.mCurrentRowFrame = nullptr;
       for (int32_t rowB = info.mRowIndex; rowB <= info.GetCellEndRowIndex();
@@ -5275,7 +5278,7 @@ void nsTableFrame::CalcBCBorders() {
         BCCornerInfo& bStartIEndCorner =
             (0 == rowB) ? bStartCorners[info.GetCellEndColIndex() + 1]
                         : bEndCorners[info.GetCellEndColIndex() + 1];
-        bStartIEndCorner.Update(eLogicalSideBEnd, currentBorder);
+        bStartIEndCorner.Update(LogicalSide::BEnd, currentBorder);
         tableCellMap->SetBCBorderCorner(
             LogicalCorner::BStartIEnd, *iter.mCellMap, iter.mRowGroupStart,
             rowB, info.GetCellEndColIndex(),
@@ -5283,7 +5286,7 @@ void nsTableFrame::CalcBCBorders() {
             bStartIEndCorner.bevel);
         BCCornerInfo& bEndIEndCorner =
             bEndCorners[info.GetCellEndColIndex() + 1];
-        bEndIEndCorner.Set(eLogicalSideBStart, currentBorder);
+        bEndIEndCorner.Set(LogicalSide::BStart, currentBorder);
         tableCellMap->SetBCBorderCorner(
             LogicalCorner::BEndIEnd, *iter.mCellMap, iter.mRowGroupStart, rowB,
             info.GetCellEndColIndex(), LogicalSide(bEndIEndCorner.ownerSide),
@@ -5293,7 +5296,7 @@ void nsTableFrame::CalcBCBorders() {
             currentBorder, lastBlockDirBorders[info.GetCellEndColIndex() + 1]);
         // store the border segment in the cell map and update cellBorders
         tableCellMap->SetBCBorderEdge(
-            eLogicalSideIEnd, *iter.mCellMap, iter.mRowGroupStart, rowB,
+            LogicalSide::IEnd, *iter.mCellMap, iter.mRowGroupStart, rowB,
             info.GetCellEndColIndex(), 1, currentBorder.owner,
             currentBorder.width, startSeg);
         // Set border width at inline-end (table-wide and for the cell), but
@@ -5325,7 +5328,7 @@ void nsTableFrame::CalcBCBorders() {
         if (info.GetCellEndColIndex() < damageArea.EndCol() &&
             rowB >= damageArea.StartRow() && rowB < damageArea.EndRow()) {
           tableCellMap->SetBCBorderEdge(
-              eLogicalSideIEnd, *iter.mCellMap, iter.mRowGroupStart, rowB,
+              LogicalSide::IEnd, *iter.mCellMap, iter.mRowGroupStart, rowB,
               info.GetCellEndColIndex(), segLength, currentBorder.owner,
               currentBorder.width, startSeg);
           info.SetIEndBorderWidths(currentBorder.width);
@@ -5346,7 +5349,7 @@ void nsTableFrame::CalcBCBorders() {
                 ? &bStartCorners[info.GetCellEndColIndex() + 1]
                 : &bEndCorners[info.GetCellEndColIndex() +
                                1];  // From previous row.
-        bStartIEndCorner->Update(eLogicalSideBEnd, currentBorder);
+        bStartIEndCorner->Update(LogicalSide::BEnd, currentBorder);
         // If this is a rowspan, need to consider if this "corner" is generating
         // an inline segment for the adjacent cell. e.g.
         //
@@ -5360,7 +5363,7 @@ void nsTableFrame::CalcBCBorders() {
           BCCellBorder adjacentBorder = ajaInfo.GetBStartInternalBorder();
           currentBorder = CompareBorders(!CELL_CORNER, currentBorder,
                                          adjacentBorder, INLINE_DIR);
-          bStartIEndCorner->Update(eLogicalSideIEnd, currentBorder);
+          bStartIEndCorner->Update(LogicalSide::IEnd, currentBorder);
         }
         // Check that the spanned area is inside of the invalidation area
         if (info.GetCellEndColIndex() < damageArea.EndCol() &&
@@ -5387,7 +5390,7 @@ void nsTableFrame::CalcBCBorders() {
         BCCornerInfo& bEndIEndCorner =
             (hitsSpanOnIEnd) ? bStartCorners[info.GetCellEndColIndex() + 1]
                              : bEndCorners[info.GetCellEndColIndex() + 1];
-        bEndIEndCorner.Set(eLogicalSideBStart, currentBorder);
+        bEndIEndCorner.Set(LogicalSide::BStart, currentBorder);
         priorAjaInfo = ajaInfo;
       }
     }
@@ -5400,23 +5403,24 @@ void nsTableFrame::CalcBCBorders() {
     // cells and the table, row group, row
     if (info.mNumTableRows == info.GetCellEndRowIndex() + 1) {
       // touches bEnd edge of table
-      if (!tableBorderReset[eLogicalSideBEnd]) {
+      uint8_t idxBEnd = static_cast<uint8_t>(LogicalSide::BEnd);
+      if (!tableBorderReset[idxBEnd]) {
         propData->mBEndBorderWidth = 0;
-        tableBorderReset[eLogicalSideBEnd] = true;
+        tableBorderReset[idxBEnd] = true;
       }
       for (int32_t colIdx = info.mColIndex; colIdx <= info.GetCellEndColIndex();
            colIdx++) {
         info.SetColumn(colIdx);
         BCCellBorder currentBorder = info.GetBEndEdgeBorder();
         BCCornerInfo& bEndIStartCorner = bEndCorners[colIdx];
-        bEndIStartCorner.Update(eLogicalSideIEnd, currentBorder);
+        bEndIStartCorner.Update(LogicalSide::IEnd, currentBorder);
         tableCellMap->SetBCBorderCorner(
             LogicalCorner::BEndIStart, *iter.mCellMap, iter.mRowGroupStart,
             info.GetCellEndRowIndex(), colIdx,
             LogicalSide(bEndIStartCorner.ownerSide), bEndIStartCorner.subWidth,
             bEndIStartCorner.bevel);
         BCCornerInfo& bEndIEndCorner = bEndCorners[colIdx + 1];
-        bEndIEndCorner.Update(eLogicalSideIStart, currentBorder);
+        bEndIEndCorner.Update(LogicalSide::IStart, currentBorder);
         // Store the block-end inline-end corner if it also is the block-end
         // inline-end of the overall table.
         if (info.mNumTableCols == colIdx + 1) {
@@ -5439,7 +5443,7 @@ void nsTableFrame::CalcBCBorders() {
         }
         // store the border segment in the cell map and update cellBorders
         tableCellMap->SetBCBorderEdge(
-            eLogicalSideBEnd, *iter.mCellMap, iter.mRowGroupStart,
+            LogicalSide::BEnd, *iter.mCellMap, iter.mRowGroupStart,
             info.GetCellEndRowIndex(), colIdx, 1, currentBorder.owner,
             currentBorder.width, startSeg);
         // update lastBEndBorders
@@ -5486,12 +5490,12 @@ void nsTableFrame::CalcBCBorders() {
           } else if (prevRowIndex < info.GetCellEndRowIndex() + 1) {
             // spans below the cell to the iStart side
             bStartCorners[colIdx] = bEndIStartCorner;
-            bEndIStartCorner.Set(eLogicalSideIEnd, currentBorder);
+            bEndIStartCorner.Set(LogicalSide::IEnd, currentBorder);
             update = false;
           }
         }
         if (update) {
-          bEndIStartCorner.Update(eLogicalSideIEnd, currentBorder);
+          bEndIStartCorner.Update(LogicalSide::IEnd, currentBorder);
         }
         // Check that the spanned area is inside of the invalidation area
         if (info.GetCellEndRowIndex() < damageArea.EndRow() &&
@@ -5506,7 +5510,7 @@ void nsTableFrame::CalcBCBorders() {
           // Propagate this segment down the colspan
           for (int32_t c = colIdx + 1; c < colIdx + segLength; c++) {
             BCCornerInfo& corner = bEndCorners[c];
-            corner.Set(eLogicalSideIEnd, currentBorder);
+            corner.Set(LogicalSide::IEnd, currentBorder);
             tableCellMap->SetBCBorderCorner(
                 LogicalCorner::BEndIStart, *iter.mCellMap, iter.mRowGroupStart,
                 info.GetCellEndRowIndex(), c, LogicalSide(corner.ownerSide),
@@ -5533,7 +5537,7 @@ void nsTableFrame::CalcBCBorders() {
         if (info.GetCellEndRowIndex() < damageArea.EndRow() &&
             colIdx >= damageArea.StartCol() && colIdx < damageArea.EndCol()) {
           tableCellMap->SetBCBorderEdge(
-              eLogicalSideBEnd, *iter.mCellMap, iter.mRowGroupStart,
+              LogicalSide::BEnd, *iter.mCellMap, iter.mRowGroupStart,
               info.GetCellEndRowIndex(), colIdx, segLength, currentBorder.owner,
               currentBorder.width, startSeg);
           info.SetBEndBorderWidths(currentBorder.width);
@@ -5541,7 +5545,7 @@ void nsTableFrame::CalcBCBorders() {
         }
         // update bEnd-iEnd corner
         BCCornerInfo& bEndIEndCorner = bEndCorners[colIdx + segLength];
-        bEndIEndCorner.Update(eLogicalSideIStart, currentBorder);
+        bEndIEndCorner.Update(LogicalSide::IStart, currentBorder);
       }
     }
     // o------o------o
@@ -5570,7 +5574,7 @@ void nsTableFrame::CalcBCBorders() {
           // new segment
           if (iter.mCellMap) {
             tableCellMap->ResetBStartStart(
-                eLogicalSideBEnd, *iter.mCellMap, iter.mRowGroupStart,
+                LogicalSide::BEnd, *iter.mCellMap, iter.mRowGroupStart,
                 info.GetCellEndRowIndex(), nextColIndex);
           }
         }
@@ -6248,7 +6252,7 @@ static nscoord CalcVerCornerOffset(nsPresContext* aPresContext,
       offset = (aIsStartOfSeg) ? -largeHalf : smallHalf;
     } else {
       offset =
-          (eLogicalSideBStart == aCornerOwnerSide) ? smallHalf : -largeHalf;
+          (LogicalSide::BStart == aCornerOwnerSide) ? smallHalf : -largeHalf;
     }
   } else {
     DivideBCBorderSize(aHorWidth, smallHalf, largeHalf);
@@ -6283,7 +6287,7 @@ static nscoord CalcHorCornerOffset(nsPresContext* aPresContext,
       offset = (aIsStartOfSeg) ? -largeHalf : smallHalf;
     } else {
       offset =
-          (eLogicalSideIStart == aCornerOwnerSide) ? smallHalf : -largeHalf;
+          (LogicalSide::IStart == aCornerOwnerSide) ? smallHalf : -largeHalf;
     }
   } else {
     DivideBCBorderSize(aVerWidth, smallHalf, largeHalf);
@@ -6305,7 +6309,7 @@ BCBlockDirSeg::BCBlockDirSeg()
   mCol = nullptr;
   mFirstCell = mLastCell = mAjaCell = nullptr;
   mOffsetI = mOffsetB = mLength = mWidth = mBStartBevelOffset = 0;
-  mBStartBevelSide = eLogicalSideBStart;
+  mBStartBevelSide = LogicalSide::BStart;
   mOwner = eCellOwner;
 }
 
@@ -6322,7 +6326,7 @@ void BCBlockDirSeg::Start(BCPaintBorderIterator& aIter,
                           BCPixelSize aBlockSegISize,
                           BCPixelSize aInlineSegBSize,
                           Maybe<nscoord> aEmptyRowEndBSize) {
-  LogicalSide ownerSide = eLogicalSideBStart;
+  LogicalSide ownerSide = LogicalSide::BStart;
   bool bevel = false;
 
   nscoord cornerSubWidth =
@@ -6339,7 +6343,7 @@ void BCBlockDirSeg::Start(BCPaintBorderIterator& aIter,
       bStartBevel ? presContext->DevPixelsToAppUnits(maxInlineSegBSize) : 0;
   // XXX this assumes that only corners where 2 segments join can be beveled
   mBStartBevelSide =
-      (aInlineSegBSize > 0) ? eLogicalSideIEnd : eLogicalSideIStart;
+      (aInlineSegBSize > 0) ? LogicalSide::IEnd : LogicalSide::IStart;
   if (aEmptyRowEndBSize && *aEmptyRowEndBSize < offset) {
     // This segment is starting from an empty row. This will require the the
     // starting segment to overlap with the previously drawn segment, unless the
@@ -6390,7 +6394,7 @@ void BCBlockDirSeg::Initialize(BCPaintBorderIterator& aIter) {
  */
 void BCBlockDirSeg::GetBEndCorner(BCPaintBorderIterator& aIter,
                                   BCPixelSize aInlineSegBSize) {
-  LogicalSide ownerSide = eLogicalSideBStart;
+  LogicalSide ownerSide = LogicalSide::BStart;
   nscoord cornerSubWidth = 0;
   bool bevel = false;
   if (aIter.mBCData) {
@@ -6410,7 +6414,7 @@ Maybe<BCBorderParameters> BCBlockDirSeg::BuildBorderParameters(
 
   // get the border style, color and paint the segment
   LogicalSide side =
-      aIter.IsDamageAreaIEndMost() ? eLogicalSideIEnd : eLogicalSideIStart;
+      aIter.IsDamageAreaIEndMost() ? LogicalSide::IEnd : LogicalSide::IStart;
   int32_t relColIndex = aIter.GetRelativeColIndex();
   nsTableColFrame* col = mCol;
   if (!col) ABORT1(Nothing());
@@ -6430,7 +6434,7 @@ Maybe<BCBorderParameters> BCBlockDirSeg::BuildBorderParameters(
       owner = aIter.mTable;
       break;
     case eAjaColGroupOwner:
-      side = eLogicalSideIEnd;
+      side = LogicalSide::IEnd;
       if (!aIter.IsTableIEndMost() && (relColIndex > 0)) {
         col = aIter.mBlockDirInfo[relColIndex - 1].mCol;
       }
@@ -6441,7 +6445,7 @@ Maybe<BCBorderParameters> BCBlockDirSeg::BuildBorderParameters(
       }
       break;
     case eAjaColOwner:
-      side = eLogicalSideIEnd;
+      side = LogicalSide::IEnd;
       if (!aIter.IsTableIEndMost() && (relColIndex > 0)) {
         col = aIter.mBlockDirInfo[relColIndex - 1].mCol;
       }
@@ -6466,7 +6470,7 @@ Maybe<BCBorderParameters> BCBlockDirSeg::BuildBorderParameters(
       owner = mFirstRow;
       break;
     case eAjaCellOwner:
-      side = eLogicalSideIEnd;
+      side = LogicalSide::IEnd;
       cell = mAjaCell;
       [[fallthrough]];
     case eCellOwner:
@@ -6487,7 +6491,7 @@ Maybe<BCBorderParameters> BCBlockDirSeg::BuildBorderParameters(
       (mIsBEndBevel) ? presContext->DevPixelsToAppUnits(mBEndInlineSegBSize)
                      : 0;
   LogicalSide bEndBevelSide =
-      (aInlineSegBSize > 0) ? eLogicalSideIEnd : eLogicalSideIStart;
+      (aInlineSegBSize > 0) ? LogicalSide::IEnd : LogicalSide::IStart;
 
   // Convert logical to physical sides/coordinates for DrawTableBorderSegment.
 
@@ -6733,11 +6737,11 @@ void BCBlockDirSeg::IncludeCurrentBorder(BCPaintBorderIterator& aIter) {
 BCInlineDirSeg::BCInlineDirSeg()
     : mIsIEndBevel(false),
       mIEndBevelOffset(0),
-      mIEndBevelSide(eLogicalSideBStart),
+      mIEndBevelSide(LogicalSide::BStart),
       mEndOffset(0),
       mOwner(eTableOwner) {
   mOffsetI = mOffsetB = mLength = mWidth = mIStartBevelOffset = 0;
-  mIStartBevelSide = eLogicalSideBStart;
+  mIStartBevelSide = LogicalSide::BStart;
   mFirstCell = mAjaCell = nullptr;
 }
 
@@ -6751,7 +6755,7 @@ void BCInlineDirSeg::Start(BCPaintBorderIterator& aIter,
                            BCBorderOwner aBorderOwner,
                            BCPixelSize aBEndBlockSegISize,
                            BCPixelSize aInlineSegBSize) {
-  LogicalSide cornerOwnerSide = eLogicalSideBStart;
+  LogicalSide cornerOwnerSide = LogicalSide::BStart;
   bool bevel = false;
 
   mOwner = aBorderOwner;
@@ -6769,7 +6773,7 @@ void BCInlineDirSeg::Start(BCPaintBorderIterator& aIter,
       (iStartBevel && (aInlineSegBSize > 0)) ? maxBlockSegISize : 0;
   // XXX this assumes that only corners where 2 segments join can be beveled
   mIStartBevelSide =
-      (aBEndBlockSegISize > 0) ? eLogicalSideBEnd : eLogicalSideBStart;
+      (aBEndBlockSegISize > 0) ? LogicalSide::BEnd : LogicalSide::BStart;
   mOffsetI += offset;
   mLength = -offset;
   mWidth = aInlineSegBSize;
@@ -6787,7 +6791,7 @@ void BCInlineDirSeg::Start(BCPaintBorderIterator& aIter,
  */
 void BCInlineDirSeg::GetIEndCorner(BCPaintBorderIterator& aIter,
                                    BCPixelSize aIStartSegISize) {
-  LogicalSide ownerSide = eLogicalSideBStart;
+  LogicalSide ownerSide = LogicalSide::BStart;
   nscoord cornerSubWidth = 0;
   bool bevel = false;
   if (aIter.mBCData) {
@@ -6805,7 +6809,7 @@ void BCInlineDirSeg::GetIEndCorner(BCPaintBorderIterator& aIter,
   mIEndBevelOffset =
       (mIsIEndBevel) ? presContext->DevPixelsToAppUnits(verWidth) : 0;
   mIEndBevelSide =
-      (aIStartSegISize > 0) ? eLogicalSideBEnd : eLogicalSideBStart;
+      (aIStartSegISize > 0) ? LogicalSide::BEnd : LogicalSide::BStart;
 }
 
 Maybe<BCBorderParameters> BCInlineDirSeg::BuildBorderParameters(
@@ -6814,7 +6818,7 @@ Maybe<BCBorderParameters> BCInlineDirSeg::BuildBorderParameters(
 
   // get the border style, color and paint the segment
   LogicalSide side =
-      aIter.IsDamageAreaBEndMost() ? eLogicalSideBEnd : eLogicalSideBStart;
+      aIter.IsDamageAreaBEndMost() ? LogicalSide::BEnd : LogicalSide::BStart;
   nsIFrame* rg = aIter.mRg;
   if (!rg) ABORT1(Nothing());
   nsIFrame* row = aIter.mRow;
@@ -6855,21 +6859,21 @@ Maybe<BCBorderParameters> BCInlineDirSeg::BuildBorderParameters(
       owner = aIter.mTableFirstInFlow->GetColFrame(aIter.mColIndex - 1);
       break;
     case eAjaRowGroupOwner:
-      side = eLogicalSideBEnd;
+      side = LogicalSide::BEnd;
       rg = (aIter.IsTableBEndMost()) ? aIter.mRg : aIter.mPrevRg;
       [[fallthrough]];
     case eRowGroupOwner:
       owner = rg;
       break;
     case eAjaRowOwner:
-      side = eLogicalSideBEnd;
+      side = LogicalSide::BEnd;
       row = (aIter.IsTableBEndMost()) ? aIter.mRow : aIter.mPrevRow;
       [[fallthrough]];
     case eRowOwner:
       owner = row;
       break;
     case eAjaCellOwner:
-      side = eLogicalSideBEnd;
+      side = LogicalSide::BEnd;
       // if this is null due to the damage area origin-y > 0, then the border
       // won't show up anyway
       cell = mAjaCell;
@@ -6974,14 +6978,14 @@ void BCPaintBorderIterator::StoreColumnWidth(int32_t aIndex) {
  * Determine if a block-dir segment owns the corner
  */
 bool BCPaintBorderIterator::BlockDirSegmentOwnsCorner() {
-  LogicalSide cornerOwnerSide = eLogicalSideBStart;
+  LogicalSide cornerOwnerSide = LogicalSide::BStart;
   bool bevel = false;
   if (mBCData) {
     mBCData->GetCorner(cornerOwnerSide, bevel);
   }
   // unitialized ownerside, bevel
-  return (eLogicalSideBStart == cornerOwnerSide) ||
-         (eLogicalSideBEnd == cornerOwnerSide);
+  return (LogicalSide::BStart == cornerOwnerSide) ||
+         (LogicalSide::BEnd == cornerOwnerSide);
 }
 
 /**
diff --git a/layout/tables/nsTableRowFrame.cpp b/layout/tables/nsTableRowFrame.cpp
index 1190561ee8..a6f4647429 100644
--- a/layout/tables/nsTableRowFrame.cpp
+++ b/layout/tables/nsTableRowFrame.cpp
@@ -305,7 +305,7 @@ static nscoord GetBSizeOfRowsSpannedBelowFirst(
 /**
  * Post-reflow hook. This is where the table row does its post-processing
  */
-void nsTableRowFrame::DidResize() {
+void nsTableRowFrame::DidResize(ForceAlignTopForTableCell aForceAlignTop) {
   // Resize and re-align the cell frames based on our row bsize
   nsTableFrame* tableFrame = GetTableFrame();
 
@@ -369,7 +369,7 @@ void nsTableRowFrame::DidResize() {
 
     // realign cell content based on the new bsize.  We might be able to
     // skip this if the bsize didn't change... maybe.  Hard to tell.
-    cellFrame->BlockDirAlignChild(wm, mMaxCellAscent);
+    cellFrame->BlockDirAlignChild(wm, mMaxCellAscent, aForceAlignTop);
 
     // Always store the overflow, even if the height didn't change, since
     // we'll lose part of our overflow area otherwise.
@@ -581,11 +581,8 @@ nscoord nsTableRowFrame::CalcCellActualBSize(nsTableCellFrame* aCellFrame,
 
   const auto& bsizeStyleCoord = position->BSize(aWM);
   if (bsizeStyleCoord.ConvertsToLength()) {
-    // In quirks mode, table cell isize should be content-box, but bsize
-    // should be border-box.
-    // Because of this historic anomaly, we do not use quirk.css
-    // (since we can't specify one value of box-sizing for isize and another
-    // for bsize)
+    // In quirks mode, table cell bsize should always be border-box.
+    // https://quirks.spec.whatwg.org/#the-table-cell-height-box-sizing-quirk
     specifiedBSize = bsizeStyleCoord.ToLength();
     if (PresContext()->CompatibilityMode() != eCompatibility_NavQuirks &&
         position->mBoxSizing == StyleBoxSizing::Content) {
@@ -956,7 +953,6 @@ void nsTableRowFrame::Reflow(nsPresContext* aPresContext,
                              nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableRowFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   WritingMode wm = aReflowInput.GetWritingMode();
@@ -999,17 +995,14 @@ void nsTableRowFrame::Reflow(nsPresContext* aPresContext,
   PushDirtyBitToAbsoluteFrames();
 }
 
-/**
- * This function is called by the row group frame's SplitRowGroup() code when
- * pushing a row frame that has cell frames that span into it. The cell frame
- * should be reflowed with the specified height
- */
 nscoord nsTableRowFrame::ReflowCellFrame(nsPresContext* aPresContext,
                                          const ReflowInput& aReflowInput,
                                          bool aIsTopOfPage,
                                          nsTableCellFrame* aCellFrame,
                                          nscoord aAvailableBSize,
                                          nsReflowStatus& aStatus) {
+  MOZ_ASSERT(aPresContext->IsPaginated(),
+             "ReflowCellFrame currently supports only paged media!");
   MOZ_ASSERT(aAvailableBSize != NS_UNCONSTRAINEDSIZE,
              "Why split cell frame if available bsize is unconstrained?");
   WritingMode wm = aReflowInput.GetWritingMode();
@@ -1049,7 +1042,8 @@ nscoord nsTableRowFrame::ReflowCellFrame(nsPresContext* aPresContext,
   // XXX What happens if this cell has 'vertical-align: baseline' ?
   // XXX Why is it assumed that the cell's ascent hasn't changed ?
   if (isCompleteAndNotTruncated) {
-    aCellFrame->BlockDirAlignChild(wm, mMaxCellAscent);
+    aCellFrame->BlockDirAlignChild(wm, mMaxCellAscent,
+                                   ForceAlignTopForTableCell::Yes);
   }
 
   nsTableFrame::InvalidateTableFrame(
diff --git a/layout/tables/nsTableRowFrame.h b/layout/tables/nsTableRowFrame.h
index 1d68a534c3..e24be1ea23 100644
--- a/layout/tables/nsTableRowFrame.h
+++ b/layout/tables/nsTableRowFrame.h
@@ -15,6 +15,11 @@ class nsTableCellFrame;
 namespace mozilla {
 class PresShell;
 struct TableCellReflowInput;
+
+// Yes if table-cells should use 'vertical-align:top' in
+// nsTableCellFrame::BlockDirAlignChild(). This is a hack to workaround our
+// current table row group fragmentation to avoid data loss.
+enum class ForceAlignTopForTableCell : uint8_t { No, Yes };
 }  // namespace mozilla
 
 /**
@@ -104,7 +109,8 @@ class nsTableRowFrame : public nsContainerFrame {
               const ReflowInput& aReflowInput,
               nsReflowStatus& aStatus) override;
 
-  void DidResize();
+  void DidResize(mozilla::ForceAlignTopForTableCell aForceAlignTop =
+                     mozilla::ForceAlignTopForTableCell::No);
 
 #ifdef DEBUG_FRAME_DUMP
   nsresult GetFrameName(nsAString& aResult) const override;
@@ -145,7 +151,11 @@ class nsTableRowFrame : public nsContainerFrame {
   // See nsTableFrame.h
   void AddDeletedRowIndex();
 
-  /** used by row group frame code */
+  /**
+   * This function is called by the row group frame's SplitRowGroup() code when
+   * pushing a row frame that has cell frames that span into it. The cell frame
+   * should be reflowed with the specified available block-size.
+   */
   nscoord ReflowCellFrame(nsPresContext* aPresContext,
                           const ReflowInput& aReflowInput, bool aIsTopOfPage,
                           nsTableCellFrame* aCellFrame, nscoord aAvailableBSize,
diff --git a/layout/tables/nsTableRowGroupFrame.cpp b/layout/tables/nsTableRowGroupFrame.cpp
index f8dac61386..9ae8a59a90 100644
--- a/layout/tables/nsTableRowGroupFrame.cpp
+++ b/layout/tables/nsTableRowGroupFrame.cpp
@@ -1122,7 +1122,7 @@ void nsTableRowGroupFrame::SplitRowGroup(nsPresContext* aPresContext,
         FinishReflowChild(rowFrame, aPresContext, rowMetrics, &rowReflowInput,
                           wm, dummyPos, dummyContainerSize,
                           ReflowChildFlags::NoMoveFrame);
-        rowFrame->DidResize();
+        rowFrame->DidResize(ForceAlignTopForTableCell::Yes);
 
         if (!aRowForcedPageBreak && !aStatus.IsFullyComplete() &&
             ShouldAvoidBreakInside(aReflowInput)) {
@@ -1324,7 +1324,6 @@ void nsTableRowGroupFrame::Reflow(nsPresContext* aPresContext,
                                   nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableRowGroupFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Row geometry may be going to change so we need to invalidate any row
diff --git a/layout/tables/nsTableWrapperFrame.cpp b/layout/tables/nsTableWrapperFrame.cpp
index a3e957c4fd..aa898ddf6f 100644
--- a/layout/tables/nsTableWrapperFrame.cpp
+++ b/layout/tables/nsTableWrapperFrame.cpp
@@ -242,7 +242,6 @@ ComputedStyle* nsTableWrapperFrame::GetParentComputedStyle(
 nscoord nsTableWrapperFrame::GetMinISize(gfxContext* aRenderingContext) {
   nscoord iSize = nsLayoutUtils::IntrinsicForContainer(
       aRenderingContext, InnerTableFrame(), IntrinsicISizeType::MinISize);
-  DISPLAY_MIN_INLINE_SIZE(this, iSize);
   if (mCaptionFrames.NotEmpty()) {
     nscoord capISize = nsLayoutUtils::IntrinsicForContainer(
         aRenderingContext, mCaptionFrames.FirstChild(),
@@ -256,10 +255,7 @@ nscoord nsTableWrapperFrame::GetMinISize(gfxContext* aRenderingContext) {
 
 /* virtual */
 nscoord nsTableWrapperFrame::GetPrefISize(gfxContext* aRenderingContext) {
-  nscoord maxISize;
-  DISPLAY_PREF_INLINE_SIZE(this, maxISize);
-
-  maxISize = nsLayoutUtils::IntrinsicForContainer(
+  nscoord maxISize = nsLayoutUtils::IntrinsicForContainer(
       aRenderingContext, InnerTableFrame(), IntrinsicISizeType::PrefISize);
   if (mCaptionFrames.NotEmpty()) {
     // Don't let the caption's pref isize expand the table's pref isize.
@@ -547,7 +543,7 @@ ComputeSizeFlags nsTableWrapperFrame::CreateComputeSizeFlagsForChild() const {
   // Shrink-wrap child frames by default, except if we're a stretched grid item.
   if (MOZ_UNLIKELY(IsGridItem())) {
     auto* gridContainer = static_cast<nsGridContainerFrame*>(GetParent());
-    if (gridContainer->GridItemShouldStretch(this, eLogicalAxisInline)) {
+    if (gridContainer->GridItemShouldStretch(this, LogicalAxis::Inline)) {
       return {};
     }
   }
@@ -691,7 +687,6 @@ void nsTableWrapperFrame::Reflow(nsPresContext* aPresContext,
                                  nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsTableWrapperFrame");
-  DISPLAY_REFLOW(aPresContext, this, aOuterRI, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   // Initialize out parameters
diff --git a/layout/tools/reftest/mach_commands.py b/layout/tools/reftest/mach_commands.py
index 8cb1164332..dd4c8ea63a 100644
--- a/layout/tools/reftest/mach_commands.py
+++ b/layout/tools/reftest/mach_commands.py
@@ -160,10 +160,6 @@ class ReftestRunner(MozbuildObject):
             args.e10s = False
             print("using e10s=False for non-geckoview app")
 
-        # Disable fission until geckoview supports fission by default.
-        # Need fission on Android? Use '--setpref fission.autostart=true'
-        args.disableFission = True
-
         # A symlink and some path manipulations are required so that test
         # manifests can be found both locally and remotely (via a url)
         # using the same relative path.
diff --git a/layout/tools/reftest/manifest.sys.mjs b/layout/tools/reftest/manifest.sys.mjs
index 4be0afde57..a4a8ed126f 100644
--- a/layout/tools/reftest/manifest.sys.mjs
+++ b/layout/tools/reftest/manifest.sys.mjs
@@ -677,6 +677,9 @@ function BuildConditionSandbox(aURL) {
     sandbox.d2d &&
     sandbox.gpuProcess;
 
+  sandbox.mozinfo = Services.prefs.getStringPref("sandbox.mozinfo", null);
+  sandbox.os_version = sandbox.mozinfo.os_version;
+
   sandbox.layersGPUAccelerated = g.windowUtils.layerManagerType != "Basic";
   sandbox.d3d11 = g.windowUtils.layerManagerType == "Direct3D 11";
   sandbox.d3d9 = g.windowUtils.layerManagerType == "Direct3D 9";
diff --git a/layout/tools/reftest/reftest.sys.mjs b/layout/tools/reftest/reftest.sys.mjs
index 1040470967..0f103c5816 100644
--- a/layout/tools/reftest/reftest.sys.mjs
+++ b/layout/tools/reftest/reftest.sys.mjs
@@ -1423,7 +1423,9 @@ function RecordResult(testRunTime, errorMsg, typeSpecificResults) {
         // branch, 'equal' must be false so let's assert that to guard
         // against logic errors.
         if (equal) {
-          throw new Error("Logic error in reftest.jsm fuzzy test handling!");
+          throw new Error(
+            "Logic error in reftest.sys.mjs fuzzy test handling!"
+          );
         }
         output = { s: ["PASS", "FAIL"], n: "UnexpectedPass" };
       } else {
diff --git a/layout/tools/reftest/runreftest.py b/layout/tools/reftest/runreftest.py
index cf314c99b5..e97a6de5d7 100644
--- a/layout/tools/reftest/runreftest.py
+++ b/layout/tools/reftest/runreftest.py
@@ -462,6 +462,9 @@ class RefTest(object):
         # config specific flags
         prefs["sandbox.apple_silicon"] = mozinfo.info.get("apple_silicon", False)
 
+        prefs["sandbox.mozinfo"] = json.dumps(mozinfo.info)
+        prefs["sandbox.os_version"] = mozinfo.info.get("os_version", "")
+
         # Set tests to run or manifests to parse.
         if tests:
             testlist = os.path.join(profile.profile, "reftests.json")
@@ -482,22 +485,6 @@ class RefTest(object):
             if options.thisChunk:
                 prefs["reftest.thisChunk"] = options.thisChunk
 
-        # Bug 1262954: For winXP + e10s disable acceleration
-        if (
-            platform.system() in ("Windows", "Microsoft")
-            and "5.1" in platform.version()
-            and options.e10s
-        ):
-            prefs["layers.acceleration.disabled"] = True
-
-        # Bug 1300355: Disable canvas cache for win7 as it uses
-        # too much memory and causes OOMs.
-        if (
-            platform.system() in ("Windows", "Microsoft")
-            and "6.1" in platform.version()
-        ):
-            prefs["reftest.nocache"] = True
-
         if options.marionette:
             # options.marionette can specify host:port
             port = options.marionette.split(":")[1]
diff --git a/layout/xul/nsMenuPopupFrame.cpp b/layout/xul/nsMenuPopupFrame.cpp
index 8ebb8b01d5..17993c8466 100644
--- a/layout/xul/nsMenuPopupFrame.cpp
+++ b/layout/xul/nsMenuPopupFrame.cpp
@@ -491,19 +491,13 @@ void nsMenuPopupFrame::TweakMinPrefISize(nscoord& aSize) {
 }
 
 nscoord nsMenuPopupFrame::GetMinISize(gfxContext* aRC) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
-  result = nsBlockFrame::GetMinISize(aRC);
+  nscoord result = nsBlockFrame::GetMinISize(aRC);
   TweakMinPrefISize(result);
   return result;
 }
 
 nscoord nsMenuPopupFrame::GetPrefISize(gfxContext* aRC) {
-  nscoord result;
-  DISPLAY_PREF_INLINE_SIZE(this, result);
-
-  result = nsBlockFrame::GetPrefISize(aRC);
+  nscoord result = nsBlockFrame::GetPrefISize(aRC);
   TweakMinPrefISize(result);
   return result;
 }
@@ -514,7 +508,6 @@ void nsMenuPopupFrame::Reflow(nsPresContext* aPresContext,
                               nsReflowStatus& aStatus) {
   MarkInReflow();
   DO_GLOBAL_REFLOW_COUNT("nsMenuPopupFrame");
-  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 
   const auto wm = GetWritingMode();
@@ -2186,6 +2179,12 @@ nsMargin nsMenuPopupFrame::GetMargin() const {
     margin.left += auOffset.x;
     margin.right += auOffset.x;
   }
+  if (mPopupType == PopupType::Tooltip && !IsAnchored()) {
+    const auto auOffset =
+        CSSPixel::ToAppUnits(LookAndFeel::TooltipOffsetVertical());
+    margin.top += auOffset;
+    margin.bottom += auOffset;
+  }
   return margin;
 }
 
@@ -2246,7 +2245,8 @@ void nsMenuPopupFrame::MoveTo(const CSSPoint& aPos, bool aUpdateAttrs,
 void nsMenuPopupFrame::MoveToAnchor(nsIContent* aAnchorContent,
                                     const nsAString& aPosition, int32_t aXPos,
                                     int32_t aYPos, bool aAttributesOverride) {
-  NS_ASSERTION(IsVisible(), "popup must be visible to move it");
+  NS_ASSERTION(IsVisibleOrShowing(),
+               "popup must be visible or showing to move it");
 
   nsPopupState oldstate = mPopupState;
   InitializePopup(aAnchorContent, mTriggerContent, aPosition, aXPos, aYPos,
diff --git a/layout/xul/nsXULPopupManager.cpp b/layout/xul/nsXULPopupManager.cpp
index 332d60d363..a6dbeadca7 100644
--- a/layout/xul/nsXULPopupManager.cpp
+++ b/layout/xul/nsXULPopupManager.cpp
@@ -49,6 +49,7 @@
 #include "mozilla/dom/XULMenuElement.h"
 #include "mozilla/dom/XULMenuBarElement.h"
 #include "mozilla/dom/XULPopupElement.h"
+#include "mozilla/AutoRestore.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventStateManager.h"
 #include "mozilla/LookAndFeel.h"
diff --git a/layout/xul/tree/nsTreeBodyFrame.cpp b/layout/xul/tree/nsTreeBodyFrame.cpp
index 5ccc1468cc..f585009600 100644
--- a/layout/xul/tree/nsTreeBodyFrame.cpp
+++ b/layout/xul/tree/nsTreeBodyFrame.cpp
@@ -3895,7 +3895,7 @@ void nsTreeBodyFrame::RemoveImageCacheEntry(int32_t aRowIndex,
                                             nsTreeColumn* aCol) {
   nsAutoString imageSrc;
   nsCOMPtr<nsITreeView> view = GetExistingView();
-  if (NS_FAILED(view->GetImageSrc(aRowIndex, aCol, imageSrc))) {
+  if (!view || NS_FAILED(view->GetImageSrc(aRowIndex, aCol, imageSrc))) {
     return;
   }
   nsTreeImageCacheEntry entry;