1 files changed, 650 insertions, 0 deletions
diff --git a/layout/xul/nsBox.cpp b/layout/xul/nsBox.cpp
new file mode 100644
index 0000000000..e8710d4358
--- /dev/null
+++ b/layout/xul/nsBox.cpp
@@ -0,0 +1,650 @@
+/* -*- 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/Attributes.h"
+#include "mozilla/StaticPtr.h"
+#include "nsIFrame.h"
+
+#include "nsBoxLayoutState.h"
+#include "nsBoxFrame.h"
+#include "nsDOMAttributeMap.h"
+#include "nsPresContext.h"
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "nsContainerFrame.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsITheme.h"
+#include "nsBoxLayout.h"
+#include "nsLayoutUtils.h"
+#include "FrameLayerBuilder.h"
+#include "mozilla/dom/Attr.h"
+#include "mozilla/dom/Element.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+nsresult nsIFrame::BeginXULLayout(nsBoxLayoutState& aState) {
+  // mark ourselves as dirty so no child under us
+  // can post an incremental layout.
+  // XXXldb Is this still needed?
+  AddStateBits(NS_FRAME_HAS_DIRTY_CHILDREN);
+
+  if (HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
+    // If the parent is dirty, all the children are dirty (ReflowInput
+    // does this too).
+    nsIFrame* box;
+    for (box = GetChildXULBox(this); box; box = GetNextXULBox(box))
+      box->MarkSubtreeDirty();
+  }
+
+  // Another copy-over from ReflowInput.
+  // Since we are in reflow, we don't need to store these properties anymore.
+  RemoveProperty(UsedBorderProperty());
+  RemoveProperty(UsedPaddingProperty());
+  RemoveProperty(UsedMarginProperty());
+
+  return NS_OK;
+}
+
+nsresult nsIFrame::EndXULLayout(nsBoxLayoutState& aState) {
+  return SyncXULLayout(aState);
+}
+
+nsresult nsIFrame::GetXULClientRect(nsRect& aClientRect) {
+  aClientRect = mRect;
+  aClientRect.MoveTo(0, 0);
+
+  nsMargin borderPadding;
+  GetXULBorderAndPadding(borderPadding);
+
+  aClientRect.Deflate(borderPadding);
+
+  if (aClientRect.width < 0) aClientRect.width = 0;
+
+  if (aClientRect.height < 0) aClientRect.height = 0;
+
+  return NS_OK;
+}
+
+void nsIFrame::SetXULBounds(nsBoxLayoutState& aState, const nsRect& aRect,
+                            bool aRemoveOverflowAreas) {
+  nsRect rect(mRect);
+
+  ReflowChildFlags flags = GetXULLayoutFlags() | aState.LayoutFlags();
+
+  if ((flags & ReflowChildFlags::NoMoveFrame) ==
+      ReflowChildFlags::NoMoveFrame) {
+    SetSize(aRect.Size());
+  } else {
+    SetRect(aRect);
+  }
+
+  // Nuke the overflow area. The caller is responsible for restoring
+  // it if necessary.
+  if (aRemoveOverflowAreas) {
+    // remove the previously stored overflow area
+    ClearOverflowRects();
+  }
+
+  if (!(flags & ReflowChildFlags::NoMoveView)) {
+    nsContainerFrame::PositionFrameView(this);
+    if ((rect.x != aRect.x) || (rect.y != aRect.y))
+      nsContainerFrame::PositionChildViews(this);
+  }
+}
+
+nsresult nsIFrame::GetXULBorderAndPadding(nsMargin& aBorderAndPadding) {
+  aBorderAndPadding.SizeTo(0, 0, 0, 0);
+  nsresult rv = GetXULBorder(aBorderAndPadding);
+  if (NS_FAILED(rv)) return rv;
+
+  nsMargin padding;
+  rv = GetXULPadding(padding);
+  if (NS_FAILED(rv)) return rv;
+
+  aBorderAndPadding += padding;
+
+  return rv;
+}
+
+nsresult nsIFrame::GetXULBorder(nsMargin& aBorder) {
+  aBorder.SizeTo(0, 0, 0, 0);
+
+  StyleAppearance appearance = StyleDisplay()->EffectiveAppearance();
+  if (appearance != StyleAppearance::None) {
+    // Go to the theme for the border.
+    nsPresContext* pc = PresContext();
+    nsITheme* theme = pc->Theme();
+    if (theme->ThemeSupportsWidget(pc, this, appearance)) {
+      LayoutDeviceIntMargin margin =
+          theme->GetWidgetBorder(pc->DeviceContext(), this, appearance);
+      aBorder =
+          LayoutDevicePixel::ToAppUnits(margin, pc->AppUnitsPerDevPixel());
+      return NS_OK;
+    }
+  }
+
+  aBorder = StyleBorder()->GetComputedBorder();
+
+  return NS_OK;
+}
+
+nsresult nsIFrame::GetXULPadding(nsMargin& aBorderAndPadding) {
+  StyleAppearance appearance = StyleDisplay()->EffectiveAppearance();
+  if (appearance != StyleAppearance::None) {
+    // Go to the theme for the padding.
+    nsPresContext* pc = PresContext();
+    nsITheme* theme = pc->Theme();
+    if (theme->ThemeSupportsWidget(pc, this, appearance)) {
+      LayoutDeviceIntMargin padding;
+      bool useThemePadding = theme->GetWidgetPadding(pc->DeviceContext(), this,
+                                                     appearance, &padding);
+      if (useThemePadding) {
+        aBorderAndPadding =
+            LayoutDevicePixel::ToAppUnits(padding, pc->AppUnitsPerDevPixel());
+        return NS_OK;
+      }
+    }
+  }
+
+  aBorderAndPadding.SizeTo(0, 0, 0, 0);
+  StylePadding()->GetPadding(aBorderAndPadding);
+
+  return NS_OK;
+}
+
+nsresult nsIFrame::GetXULMargin(nsMargin& aMargin) {
+  aMargin.SizeTo(0, 0, 0, 0);
+  StyleMargin()->GetMargin(aMargin);
+
+  return NS_OK;
+}
+
+void nsIFrame::XULSizeNeedsRecalc(nsSize& aSize) {
+  aSize.width = -1;
+  aSize.height = -1;
+}
+
+void nsIFrame::XULCoordNeedsRecalc(nscoord& aCoord) { aCoord = -1; }
+
+bool nsIFrame::XULNeedsRecalc(const nsSize& aSize) {
+  return (aSize.width == -1 || aSize.height == -1);
+}
+
+bool nsIFrame::XULNeedsRecalc(nscoord aCoord) { return (aCoord == -1); }
+
+nsSize nsIFrame::GetUncachedXULPrefSize(nsBoxLayoutState& aBoxLayoutState) {
+  NS_ASSERTION(aBoxLayoutState.GetRenderingContext(),
+               "must have rendering context");
+
+  nsSize pref(0, 0);
+  DISPLAY_PREF_SIZE(this, pref);
+
+  if (IsXULCollapsed()) {
+    return pref;
+  }
+
+  AddXULBorderAndPadding(pref);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULPrefSize(this, pref, widthSet, heightSet);
+
+  nsSize minSize = GetXULMinSize(aBoxLayoutState);
+  nsSize maxSize = GetXULMaxSize(aBoxLayoutState);
+  return XULBoundsCheck(minSize, pref, maxSize);
+}
+
+nsSize nsIFrame::GetUncachedXULMinSize(nsBoxLayoutState& aBoxLayoutState) {
+  NS_ASSERTION(aBoxLayoutState.GetRenderingContext(),
+               "must have rendering context");
+
+  nsSize min(0, 0);
+  DISPLAY_MIN_SIZE(this, min);
+
+  if (IsXULCollapsed()) {
+    return min;
+  }
+
+  AddXULBorderAndPadding(min);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULMinSize(this, min, widthSet, heightSet);
+  return min;
+}
+
+nsSize nsIFrame::GetXULMinSizeForScrollArea(nsBoxLayoutState& aBoxLayoutState) {
+  return nsSize(0, 0);
+}
+
+nsSize nsIFrame::GetUncachedXULMaxSize(nsBoxLayoutState& aBoxLayoutState) {
+  NS_ASSERTION(aBoxLayoutState.GetRenderingContext(),
+               "must have rendering context");
+
+  nsSize maxSize(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  DISPLAY_MAX_SIZE(this, maxSize);
+
+  if (IsXULCollapsed()) {
+    return maxSize;
+  }
+
+  AddXULBorderAndPadding(maxSize);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULMaxSize(this, maxSize, widthSet, heightSet);
+  return maxSize;
+}
+
+bool nsIFrame::IsXULCollapsed() {
+  return StyleVisibility()->mVisible == StyleVisibility::Collapse;
+}
+
+nsresult nsIFrame::XULLayout(nsBoxLayoutState& aState) {
+  NS_ASSERTION(aState.GetRenderingContext(), "must have rendering context");
+
+  nsIFrame* box = static_cast<nsIFrame*>(this);
+  DISPLAY_LAYOUT(box);
+
+  box->BeginXULLayout(aState);
+
+  box->DoXULLayout(aState);
+
+  box->EndXULLayout(aState);
+
+  return NS_OK;
+}
+
+bool nsIFrame::DoesClipChildrenInBothAxes() {
+  const nsStyleDisplay* display = StyleDisplay();
+  return display->mOverflowX == StyleOverflow::Clip &&
+         display->mOverflowY == StyleOverflow::Clip;
+}
+
+nsresult nsIFrame::SyncXULLayout(nsBoxLayoutState& aBoxLayoutState) {
+  /*
+  if (IsXULCollapsed()) {
+    CollapseChild(aBoxLayoutState, this, true);
+    return NS_OK;
+  }
+  */
+
+  if (HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
+    XULRedraw(aBoxLayoutState);
+  }
+
+  RemoveStateBits(NS_FRAME_HAS_DIRTY_CHILDREN | NS_FRAME_IS_DIRTY |
+                  NS_FRAME_FIRST_REFLOW | NS_FRAME_IN_REFLOW);
+
+  nsPresContext* presContext = aBoxLayoutState.PresContext();
+
+  ReflowChildFlags flags = GetXULLayoutFlags() | aBoxLayoutState.LayoutFlags();
+
+  nsRect inkOverflow;
+
+  if (XULComputesOwnOverflowArea()) {
+    inkOverflow = InkOverflowRect();
+  } else {
+    nsRect rect(nsPoint(0, 0), GetSize());
+    OverflowAreas overflowAreas(rect, rect);
+    if (!DoesClipChildrenInBothAxes() && !IsXULCollapsed()) {
+      // See if our child frames caused us to overflow after being laid
+      // out. If so, store the overflow area.  This normally can't happen
+      // in XUL, but it can happen with the CSS 'outline' property and
+      // possibly with other exotic stuff (e.g. relatively positioned
+      // frames in HTML inside XUL).
+      nsLayoutUtils::UnionChildOverflow(this, overflowAreas);
+    }
+
+    FinishAndStoreOverflow(overflowAreas, GetSize());
+    inkOverflow = overflowAreas.InkOverflow();
+  }
+
+  nsView* view = GetView();
+  if (view) {
+    // Make sure the frame's view is properly sized and positioned and has
+    // things like opacity correct
+    nsContainerFrame::SyncFrameViewAfterReflow(presContext, this, view,
+                                               inkOverflow, flags);
+  }
+
+  return NS_OK;
+}
+
+nsresult nsIFrame::XULRedraw(nsBoxLayoutState& aState) {
+  if (aState.PaintingDisabled()) return NS_OK;
+
+  // nsStackLayout, at least, expects us to repaint descendants even
+  // if a damage rect is provided
+  InvalidateFrameSubtree();
+
+  return NS_OK;
+}
+
+bool nsIFrame::AddXULPrefSize(nsIFrame* aBox, nsSize& aSize, bool& aWidthSet,
+                              bool& aHeightSet) {
+  aWidthSet = false;
+  aHeightSet = false;
+
+  // add in the css min, max, pref
+  const nsStylePosition* position = aBox->StylePosition();
+
+  // see if the width or height was specifically set
+  // XXX Handle eStyleUnit_Enumerated?
+  // (Handling the eStyleUnit_Enumerated types requires
+  // GetXULPrefSize/GetXULMinSize methods that don't consider
+  // (min-/max-/)(width/height) properties.)
+  const auto& width = position->mWidth;
+  if (width.ConvertsToLength()) {
+    aSize.width = std::max(0, width.ToLength());
+    aWidthSet = true;
+  }
+
+  const auto& height = position->mHeight;
+  if (height.ConvertsToLength()) {
+    aSize.height = std::max(0, height.ToLength());
+    aHeightSet = true;
+  }
+
+  nsIContent* content = aBox->GetContent();
+  // ignore 'height' and 'width' attributes if the actual element is not XUL
+  // For example, we might be magic XUL frames whose primary content is an HTML
+  // <select>
+  if (content && content->IsXULElement()) {
+    nsAutoString value;
+    nsresult error;
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::width, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+
+      aSize.width = nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      aWidthSet = true;
+    }
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::height, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+
+      aSize.height =
+          nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      aHeightSet = true;
+    }
+  }
+
+  return (aWidthSet && aHeightSet);
+}
+
+// This returns the scrollbar width we want to use when either native
+// theme is disabled, or the native theme claims that it doesn't support
+// scrollbar.
+static nscoord GetScrollbarWidthNoTheme(nsIFrame* aBox) {
+  ComputedStyle* scrollbarStyle = nsLayoutUtils::StyleForScrollbar(aBox);
+  switch (scrollbarStyle->StyleUIReset()->mScrollbarWidth) {
+    default:
+    case StyleScrollbarWidth::Auto:
+      return 12 * AppUnitsPerCSSPixel();
+    case StyleScrollbarWidth::Thin:
+      return 6 * AppUnitsPerCSSPixel();
+    case StyleScrollbarWidth::None:
+      return 0;
+  }
+}
+
+bool nsIFrame::AddXULMinSize(nsIFrame* aBox, nsSize& aSize, bool& aWidthSet,
+                             bool& aHeightSet) {
+  aWidthSet = false;
+  aHeightSet = false;
+
+  bool canOverride = true;
+
+  nsPresContext* pc = aBox->PresContext();
+
+  // See if a native theme wants to supply a minimum size.
+  const nsStyleDisplay* display = aBox->StyleDisplay();
+  if (display->HasAppearance()) {
+    nsITheme* theme = pc->Theme();
+    StyleAppearance appearance = display->EffectiveAppearance();
+    if (theme->ThemeSupportsWidget(pc, aBox, appearance)) {
+      LayoutDeviceIntSize size;
+      theme->GetMinimumWidgetSize(pc, aBox, appearance, &size, &canOverride);
+      if (size.width) {
+        aSize.width = pc->DevPixelsToAppUnits(size.width);
+        aWidthSet = true;
+      }
+      if (size.height) {
+        aSize.height = pc->DevPixelsToAppUnits(size.height);
+        aHeightSet = true;
+      }
+    } else {
+      switch (appearance) {
+        case StyleAppearance::ScrollbarVertical:
+          aSize.width = GetScrollbarWidthNoTheme(aBox);
+          aWidthSet = true;
+          break;
+        case StyleAppearance::ScrollbarHorizontal:
+          aSize.height = GetScrollbarWidthNoTheme(aBox);
+          aHeightSet = true;
+          break;
+        default:
+          break;
+      }
+    }
+  }
+
+  // add in the css min, max, pref
+  const nsStylePosition* position = aBox->StylePosition();
+  const auto& minWidth = position->mMinWidth;
+  if (minWidth.ConvertsToLength()) {
+    nscoord min = minWidth.ToLength();
+    if (!aWidthSet || (min > aSize.width && canOverride)) {
+      aSize.width = min;
+      aWidthSet = true;
+    }
+  } else if (minWidth.ConvertsToPercentage()) {
+    NS_ASSERTION(minWidth.ToPercentage() == 0.0f,
+                 "Non-zero percentage values not currently supported");
+    aSize.width = 0;
+    aWidthSet = true;  // FIXME: should we really do this for
+                       // nonzero values?
+  }
+  // XXX Handle ExtremumLength?
+  // (Handling them  requires GetXULPrefSize/GetXULMinSize methods that don't
+  // consider (min-/max-/)(width/height) properties.
+  // calc() with percentage is treated like '0' (unset)
+
+  const auto& minHeight = position->mMinHeight;
+  if (minHeight.ConvertsToLength()) {
+    nscoord min = minHeight.ToLength();
+    if (!aHeightSet || (min > aSize.height && canOverride)) {
+      aSize.height = min;
+      aHeightSet = true;
+    }
+  } else if (minHeight.ConvertsToPercentage()) {
+    NS_ASSERTION(position->mMinHeight.ToPercentage() == 0.0f,
+                 "Non-zero percentage values not currently supported");
+    aSize.height = 0;
+    aHeightSet = true;  // FIXME: should we really do this for
+                        // nonzero values?
+  }
+  // calc() with percentage is treated like '0' (unset)
+
+  nsIContent* content = aBox->GetContent();
+  if (content && content->IsXULElement()) {
+    nsAutoString value;
+    nsresult error;
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::minwidth,
+                                  value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+
+      nscoord val = nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      if (val > aSize.width) aSize.width = val;
+      aWidthSet = true;
+    }
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::minheight,
+                                  value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+
+      nscoord val = nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      if (val > aSize.height) aSize.height = val;
+
+      aHeightSet = true;
+    }
+  }
+
+  return (aWidthSet && aHeightSet);
+}
+
+bool nsIFrame::AddXULMaxSize(nsIFrame* aBox, nsSize& aSize, bool& aWidthSet,
+                             bool& aHeightSet) {
+  aWidthSet = false;
+  aHeightSet = false;
+
+  // add in the css min, max, pref
+  const nsStylePosition* position = aBox->StylePosition();
+
+  // and max
+  // see if the width or height was specifically set
+  // XXX Handle eStyleUnit_Enumerated?
+  // (Handling the eStyleUnit_Enumerated types requires
+  // GetXULPrefSize/GetXULMinSize methods that don't consider
+  // (min-/max-/)(width/height) properties.)
+  const auto& maxWidth = position->mMaxWidth;
+  if (maxWidth.ConvertsToLength()) {
+    aSize.width = maxWidth.ToLength();
+    aWidthSet = true;
+  }
+  // percentages and calc() with percentages are treated like 'none'
+
+  const auto& maxHeight = position->mMaxHeight;
+  if (maxHeight.ConvertsToLength()) {
+    aSize.height = maxHeight.ToLength();
+    aHeightSet = true;
+  }
+  // percentages and calc() with percentages are treated like 'none'
+
+  nsIContent* content = aBox->GetContent();
+  if (content && content->IsXULElement()) {
+    nsAutoString value;
+    nsresult error;
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::maxwidth,
+                                  value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+
+      nscoord val = nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      aSize.width = val;
+      aWidthSet = true;
+    }
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::maxheight,
+                                  value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+
+      nscoord val = nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      aSize.height = val;
+
+      aHeightSet = true;
+    }
+  }
+
+  return (aWidthSet || aHeightSet);
+}
+
+bool nsIFrame::AddXULFlex(nsIFrame* aBox, nscoord& aFlex) {
+  bool flexSet = false;
+
+  // get the flexibility
+  aFlex = aBox->StyleXUL()->mBoxFlex;
+
+  // attribute value overrides CSS
+  nsIContent* content = aBox->GetContent();
+  if (content && content->IsXULElement()) {
+    nsresult error;
+    nsAutoString value;
+
+    content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::flex, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      aFlex = value.ToInteger(&error);
+      flexSet = true;
+    }
+  }
+
+  if (aFlex < 0) aFlex = 0;
+  if (aFlex >= nscoord_MAX) aFlex = nscoord_MAX - 1;
+
+  return flexSet || aFlex > 0;
+}
+
+void nsIFrame::AddXULBorderAndPadding(nsSize& aSize) {
+  AddXULBorderAndPadding(this, aSize);
+}
+
+void nsIFrame::AddXULBorderAndPadding(nsIFrame* aBox, nsSize& aSize) {
+  nsMargin borderPadding(0, 0, 0, 0);
+  aBox->GetXULBorderAndPadding(borderPadding);
+  AddXULMargin(aSize, borderPadding);
+}
+
+void nsIFrame::AddXULMargin(nsIFrame* aChild, nsSize& aSize) {
+  nsMargin margin(0, 0, 0, 0);
+  aChild->GetXULMargin(margin);
+  AddXULMargin(aSize, margin);
+}
+
+void nsIFrame::AddXULMargin(nsSize& aSize, const nsMargin& aMargin) {
+  if (aSize.width != NS_UNCONSTRAINEDSIZE)
+    aSize.width += aMargin.left + aMargin.right;
+
+  if (aSize.height != NS_UNCONSTRAINEDSIZE)
+    aSize.height += aMargin.top + aMargin.bottom;
+}
+
+nscoord nsIFrame::XULBoundsCheck(nscoord aMin, nscoord aPref, nscoord aMax) {
+  if (aPref > aMax) aPref = aMax;
+
+  if (aPref < aMin) aPref = aMin;
+
+  return aPref;
+}
+
+nsSize nsIFrame::XULBoundsCheckMinMax(const nsSize& aMinSize,
+                                      const nsSize& aMaxSize) {
+  return nsSize(std::max(aMaxSize.width, aMinSize.width),
+                std::max(aMaxSize.height, aMinSize.height));
+}
+
+nsSize nsIFrame::XULBoundsCheck(const nsSize& aMinSize, const nsSize& aPrefSize,
+                                const nsSize& aMaxSize) {
+  return nsSize(
+      XULBoundsCheck(aMinSize.width, aPrefSize.width, aMaxSize.width),
+      XULBoundsCheck(aMinSize.height, aPrefSize.height, aMaxSize.height));
+}
+
+/*static*/
+nsIFrame* nsIFrame::GetChildXULBox(const nsIFrame* aFrame) {
+  // box layout ends at box-wrapped frames, so don't allow these frames
+  // to report child boxes.
+  return aFrame->IsXULBoxFrame() ? aFrame->PrincipalChildList().FirstChild()
+                                 : nullptr;
+}
+
+/*static*/
+nsIFrame* nsIFrame::GetNextXULBox(const nsIFrame* aFrame) {
+  return aFrame->GetParent() && aFrame->GetParent()->IsXULBoxFrame()
+             ? aFrame->GetNextSibling()
+             : nullptr;
+}
+
+/*static*/
+nsIFrame* nsIFrame::GetParentXULBox(const nsIFrame* aFrame) {
+  return aFrame->GetParent() && aFrame->GetParent()->IsXULBoxFrame()
+             ? aFrame->GetParent()
+             : nullptr;
+}