Merging upstream version 125.0.1.

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

40 files changed, 944 insertions, 651 deletions

diff --git a/editor/AsyncSpellCheckTestHelper.sys.mjs b/editor/AsyncSpellCheckTestHelper.sys.mjs
index 6ceb2a86b2..748e54df66 100644
--- a/editor/AsyncSpellCheckTestHelper.sys.mjs
+++ b/editor/AsyncSpellCheckTestHelper.sys.mjs
@@ -50,7 +50,7 @@ export function maybeOnSpellCheck(editableElement, callback) {
   let waitingForEnded = isc && isc.spellCheckPending;
   let count = 0;
 
-  function observe(subj, topic, data) {
+  function observe(subj, topic) {
     if (subj != editor) {
       return;
     }
diff --git a/editor/composer/res/EditorOverride.css b/editor/composer/res/EditorOverride.css
index a1733b76b1..c4c642705d 100644
--- a/editor/composer/res/EditorOverride.css
+++ b/editor/composer/res/EditorOverride.css
@@ -70,10 +70,6 @@ label {
     user-select: all !important;
 }
 
-::-moz-display-comboboxcontrol-frame {
-  user-select: text !important;
-}
-
 option {
   user-select: text !important;
 }
diff --git a/editor/composer/test/test_bug1266815.html b/editor/composer/test/test_bug1266815.html
index 1c565fb2c1..1c0a6d87e1 100644
--- a/editor/composer/test/test_bug1266815.html
+++ b/editor/composer/test/test_bug1266815.html
@@ -41,7 +41,7 @@ var helperAppDlgPromise = new Promise(function(resolve) {
   }
 
   HelperAppLauncherDialog.prototype = {
-    show(aLauncher, aWindowContext, aReason) {
+    show() {
       ok(true, "Whether showing Dialog");
       resolve();
       registrar.unregisterFactory(MOCK_HELPERAPP_DIALOG_CID,
diff --git a/editor/composer/test/test_bug434998.xhtml b/editor/composer/test/test_bug434998.xhtml
index db2261e3a5..0aad78f198 100644
--- a/editor/composer/test/test_bug434998.xhtml
+++ b/editor/composer/test/test_bug434998.xhtml
@@ -44,7 +44,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=434998
     QueryInterface: ChromeUtils.generateQI(["nsIWebProgressListener",
                                             "nsISupportsWeakReference"]),
 
-    onStateChange(aWebProgress, aRequest, aStateFlags, aStatus)
+    onStateChange(aWebProgress, aRequest, aStateFlags)
     {
       if (aStateFlags & Ci.nsIWebProgressListener.STATE_STOP)
       {
@@ -65,25 +65,23 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=434998
     },
 
 
-    onProgressChange(aWebProgress, aRequest,
-                                aCurSelfProgress, aMaxSelfProgress,
-                                aCurTotalProgress, aMaxTotalProgress)
+    onProgressChange()
     {
   },
 
-  onLocationChange(aWebProgress, aRequest, aLocation, aFlags)
+  onLocationChange()
     {
     },
 
-    onStatusChange(aWebProgress, aRequest, aStatus, aMessage)
+    onStatusChange()
     {
     },
 
-    onSecurityChange(aWebProgress, aRequest, aState)
+    onSecurityChange()
     {
     },
 
-    onContentBlockingEvent(aWebProgress, aRequest, aEvent)
+    onContentBlockingEvent()
     {
     },
 
diff --git a/editor/libeditor/AutoRangeArray.cpp b/editor/libeditor/AutoRangeArray.cpp
index be89671760..57b9b26a35 100644
--- a/editor/libeditor/AutoRangeArray.cpp
+++ b/editor/libeditor/AutoRangeArray.cpp
@@ -86,6 +86,15 @@ AutoRangeArray::~AutoRangeArray() {
   }
 }
 
+AutoRangeArray::AutoRangeArray(nsRange& aRange) {
+  MOZ_ASSERT(aRange.IsPositioned());
+  if (NS_WARN_IF(!aRange.IsPositioned())) {
+    return;
+  }
+  mRanges.AppendElement(aRange);
+  mAnchorFocusRange = &aRange;
+}
+
 // static
 bool AutoRangeArray::IsEditableRange(const dom::AbstractRange& aRange,
                                      const Element& aEditingHost) {
diff --git a/editor/libeditor/AutoRangeArray.h b/editor/libeditor/AutoRangeArray.h
index e2dd2e0149..3f3c4bf5b6 100644
--- a/editor/libeditor/AutoRangeArray.h
+++ b/editor/libeditor/AutoRangeArray.h
@@ -43,6 +43,7 @@ class MOZ_STACK_CLASS AutoRangeArray final {
   explicit AutoRangeArray(const EditorDOMRangeBase<PointType>& aRange);
   template <typename PT, typename CT>
   explicit AutoRangeArray(const EditorDOMPointBase<PT, CT>& aPoint);
+  explicit AutoRangeArray(nsRange& aRange);
   // The copy constructor copies everything except saved ranges.
   explicit AutoRangeArray(const AutoRangeArray& aOther);
 
diff --git a/editor/libeditor/EditorBase.cpp b/editor/libeditor/EditorBase.cpp
index 22452c59d2..e8120d93d9 100644
--- a/editor/libeditor/EditorBase.cpp
+++ b/editor/libeditor/EditorBase.cpp
@@ -4869,6 +4869,29 @@ nsresult EditorBase::DeleteSelectionWithTransaction(
   return NS_OK;
 }
 
+Result<CaretPoint, nsresult> EditorBase::DeleteRangeWithTransaction(
+    nsIEditor::EDirection aDirectionAndAmount,
+    nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete) {
+  MOZ_ASSERT(IsEditActionDataAvailable());
+  MOZ_ASSERT(!Destroyed());
+  MOZ_ASSERT(aStripWrappers == eStrip || aStripWrappers == eNoStrip);
+
+  HowToHandleCollapsedRange howToHandleCollapsedRange =
+      EditorBase::HowToHandleCollapsedRangeFor(aDirectionAndAmount);
+  if (MOZ_UNLIKELY(aRangeToDelete.Collapsed() &&
+                   howToHandleCollapsedRange ==
+                       HowToHandleCollapsedRange::Ignore)) {
+    return CaretPoint(EditorDOMPoint(aRangeToDelete.StartRef()));
+  }
+
+  AutoRangeArray rangesToDelete(aRangeToDelete);
+  Result<CaretPoint, nsresult> result = DeleteRangesWithTransaction(
+      aDirectionAndAmount, aStripWrappers, rangesToDelete);
+  NS_WARNING_ASSERTION(result.isOk(),
+                       "EditorBase::DeleteRangesWithTransaction() failed");
+  return result;
+}
+
 Result<CaretPoint, nsresult> EditorBase::DeleteRangesWithTransaction(
     nsIEditor::EDirection aDirectionAndAmount,
     nsIEditor::EStripWrappers aStripWrappers,
diff --git a/editor/libeditor/EditorBase.h b/editor/libeditor/EditorBase.h
index 952b8aa3f6..83f53ff215 100644
--- a/editor/libeditor/EditorBase.h
+++ b/editor/libeditor/EditorBase.h
@@ -2519,6 +2519,25 @@ class EditorBase : public nsIEditor,
                                  nsIEditor::EStripWrappers aStripWrappers);
 
   /**
+   * DeleteRangeWithTransaction() removes content in aRangeToDelete or content
+   * around collapsed aRangeToDelete with transactions and remove empty
+   * inclusive ancestor inline elements of the collapsed range after removing
+   * the contents.
+   *
+   * @param aDirectionAndAmount How much range should be removed.
+   * @param aStripWrappers      Whether the parent blocks should be removed
+   *                            when they become empty.
+   *                            Note that this must be `nsIEditor::eNoStrip`
+   *                            if this is a TextEditor because anyway it'll
+   *                            be ignored.
+   * @param aRangeToDelete     The range to delete content.
+   */
+  [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<CaretPoint, nsresult>
+  DeleteRangeWithTransaction(nsIEditor::EDirection aDirectionAndAmount,
+                             nsIEditor::EStripWrappers aStripWrappers,
+                             nsRange& aRangeToDelete);
+
+  /**
    * DeleteRangesWithTransaction() removes content in aRangesToDelete or content
    * around collapsed ranges in aRangesToDelete with transactions and remove
    * empty inclusive ancestor inline elements of collapsed ranges after
diff --git a/editor/libeditor/EditorCommands.cpp b/editor/libeditor/EditorCommands.cpp
index beb4f060ad..45f9e3198f 100644
--- a/editor/libeditor/EditorCommands.cpp
+++ b/editor/libeditor/EditorCommands.cpp
@@ -269,7 +269,8 @@ bool UndoCommand::IsCommandEnabled(Command aCommand,
   if (!aEditorBase) {
     return false;
   }
-  return aEditorBase->IsSelectionEditable() && aEditorBase->CanUndo();
+  return aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable() &&
+         aEditorBase->CanUndo();
 }
 
 nsresult UndoCommand::DoCommand(Command aCommand, EditorBase& aEditorBase,
@@ -297,7 +298,8 @@ bool RedoCommand::IsCommandEnabled(Command aCommand,
   if (!aEditorBase) {
     return false;
   }
-  return aEditorBase->IsSelectionEditable() && aEditorBase->CanRedo();
+  return aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable() &&
+         aEditorBase->CanRedo();
 }
 
 nsresult RedoCommand::DoCommand(Command aCommand, EditorBase& aEditorBase,
@@ -548,7 +550,7 @@ bool SwitchTextDirectionCommand::IsCommandEnabled(
   if (!aEditorBase) {
     return false;
   }
-  return aEditorBase->IsSelectionEditable();
+  return aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable();
 }
 
 nsresult SwitchTextDirectionCommand::DoCommand(Command aCommand,
@@ -581,7 +583,8 @@ bool DeleteCommand::IsCommandEnabled(Command aCommand,
   // We can generally delete whenever the selection is editable.  However,
   // cmd_delete doesn't make sense if the selection is collapsed because it's
   // directionless.
-  bool isEnabled = aEditorBase->IsSelectionEditable();
+  bool isEnabled =
+      aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable();
 
   if (aCommand == Command::Delete && isEnabled) {
     return aEditorBase->CanDeleteSelection();
@@ -820,7 +823,7 @@ bool InsertPlaintextCommand::IsCommandEnabled(Command aCommand,
   if (!aEditorBase) {
     return false;
   }
-  return aEditorBase->IsSelectionEditable();
+  return aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable();
 }
 
 nsresult InsertPlaintextCommand::DoCommand(Command aCommand,
@@ -877,7 +880,7 @@ bool InsertParagraphCommand::IsCommandEnabled(Command aCommand,
   if (!aEditorBase || aEditorBase->IsSingleLineEditor()) {
     return false;
   }
-  return aEditorBase->IsSelectionEditable();
+  return aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable();
 }
 
 nsresult InsertParagraphCommand::DoCommand(Command aCommand,
@@ -918,7 +921,7 @@ bool InsertLineBreakCommand::IsCommandEnabled(Command aCommand,
   if (!aEditorBase || aEditorBase->IsSingleLineEditor()) {
     return false;
   }
-  return aEditorBase->IsSelectionEditable();
+  return aEditorBase->IsModifiable() && aEditorBase->IsSelectionEditable();
 }
 
 nsresult InsertLineBreakCommand::DoCommand(Command aCommand,
diff --git a/editor/libeditor/HTMLEditor.cpp b/editor/libeditor/HTMLEditor.cpp
index 9f4aab3dab..e9ea8887b7 100644
--- a/editor/libeditor/HTMLEditor.cpp
+++ b/editor/libeditor/HTMLEditor.cpp
@@ -719,14 +719,33 @@ void HTMLEditor::UpdateRootElement() {
 
 nsresult HTMLEditor::FocusedElementOrDocumentBecomesEditable(
     Document& aDocument, Element* aElement) {
+  const bool isInDesignMode =
+      (IsInDesignMode() && (!aElement || aElement->IsInDesignMode()));
+
   // If we should've already handled focus event, selection limiter should not
-  // be set.  Therefore, if it's set, we should do nothing here.
+  // be set.  However, IMEStateManager is not notified the pseudo focus change
+  // in this case. Therefore, we need to notify IMEStateManager of this.
   if (GetSelectionAncestorLimiter()) {
+    if (isInDesignMode) {
+      return NS_OK;
+    }
+    // Although editor is already initialized due to re-used, ISM may not
+    // create IME content observer yet. So we have to create it.
+    IMEState newState;
+    nsresult rv = GetPreferredIMEState(&newState);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("EditorBase::GetPreferredIMEState() failed");
+      return NS_OK;
+    }
+    if (const RefPtr<Element> focusedElement = GetFocusedElement()) {
+      MOZ_ASSERT(focusedElement == aElement);
+      IMEStateManager::UpdateIMEState(newState, focusedElement, *this);
+    }
     return NS_OK;
   }
   // If we should be in the design mode, we want to handle focus event fired
   // on the document node.  Therefore, we should emulate it here.
-  if (IsInDesignMode() && (!aElement || aElement->IsInDesignMode())) {
+  if (isInDesignMode) {
     MOZ_ASSERT(&aDocument == GetDocument());
     nsresult rv = OnFocus(aDocument);
     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "HTMLEditor::OnFocus() failed");
@@ -5949,14 +5968,23 @@ bool HTMLEditor::IsEmpty() const {
     return true;
   }
 
-  // XXX Oddly, we check body or document element's state instead of
-  //     active editing host.  Must be a bug.
-  Element* bodyOrDocumentElement = GetRoot();
-  if (!bodyOrDocumentElement) {
-    return true;
+  const Element* activeElement =
+      GetDocument() ? GetDocument()->GetActiveElement() : nullptr;
+  const Element* editingHostOrBodyOrRootElement =
+      activeElement && activeElement->IsEditable()
+          ? ComputeEditingHost(*activeElement, LimitInBodyElement::No)
+          : ComputeEditingHost(LimitInBodyElement::No);
+  if (MOZ_UNLIKELY(!editingHostOrBodyOrRootElement)) {
+    // If there is no active element nor no selection range in the document,
+    // let's check entire the document as what we do traditionally.
+    editingHostOrBodyOrRootElement = GetRoot();
+    if (!editingHostOrBodyOrRootElement) {
+      return true;
+    }
   }
 
-  for (nsIContent* childContent = bodyOrDocumentElement->GetFirstChild();
+  for (nsIContent* childContent =
+           editingHostOrBodyOrRootElement->GetFirstChild();
        childContent; childContent = childContent->GetNextSibling()) {
     if (!childContent->IsText() || childContent->Length()) {
       return false;
diff --git a/editor/libeditor/HTMLEditorCommands.cpp b/editor/libeditor/HTMLEditorCommands.cpp
index 1864299a3a..ecccc7c491 100644
--- a/editor/libeditor/HTMLEditorCommands.cpp
+++ b/editor/libeditor/HTMLEditorCommands.cpp
@@ -52,7 +52,7 @@ bool StateUpdatingCommandBase::IsCommandEnabled(Command aCommand,
   if (!htmlEditor) {
     return false;
   }
-  if (!htmlEditor->IsSelectionEditable()) {
+  if (!htmlEditor->IsModifiable() || !htmlEditor->IsSelectionEditable()) {
     return false;
   }
   if (aCommand == Command::FormatAbsolutePosition) {
@@ -355,8 +355,7 @@ bool RemoveListCommand::IsCommandEnabled(Command aCommand,
   if (!htmlEditor) {
     return false;
   }
-
-  if (!htmlEditor->IsSelectionEditable()) {
+  if (!htmlEditor->IsModifiable() || !htmlEditor->IsSelectionEditable()) {
     return false;
   }
 
@@ -401,7 +400,7 @@ bool IndentCommand::IsCommandEnabled(Command aCommand,
   if (!htmlEditor) {
     return false;
   }
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult IndentCommand::DoCommand(Command aCommand, EditorBase& aEditorBase,
@@ -434,7 +433,7 @@ bool OutdentCommand::IsCommandEnabled(Command aCommand,
   if (!htmlEditor) {
     return false;
   }
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult OutdentCommand::DoCommand(Command aCommand, EditorBase& aEditorBase,
@@ -467,7 +466,7 @@ bool MultiStateCommandBase::IsCommandEnabled(Command aCommand,
     return false;
   }
   // should be disabled sometimes, like if the current selection is an image
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult MultiStateCommandBase::DoCommand(Command aCommand,
@@ -1047,7 +1046,7 @@ bool RemoveStylesCommand::IsCommandEnabled(Command aCommand,
     return false;
   }
   // test if we have any styles?
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult RemoveStylesCommand::DoCommand(Command aCommand,
@@ -1085,7 +1084,7 @@ bool IncreaseFontSizeCommand::IsCommandEnabled(Command aCommand,
     return false;
   }
   // test if we are at max size?
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult IncreaseFontSizeCommand::DoCommand(Command aCommand,
@@ -1121,7 +1120,7 @@ bool DecreaseFontSizeCommand::IsCommandEnabled(Command aCommand,
     return false;
   }
   // test if we are at min size?
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult DecreaseFontSizeCommand::DoCommand(Command aCommand,
@@ -1156,7 +1155,7 @@ bool InsertHTMLCommand::IsCommandEnabled(Command aCommand,
   if (!htmlEditor) {
     return false;
   }
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 nsresult InsertHTMLCommand::DoCommand(Command aCommand, EditorBase& aEditorBase,
@@ -1213,7 +1212,7 @@ bool InsertTagCommand::IsCommandEnabled(Command aCommand,
   if (!htmlEditor) {
     return false;
   }
-  return htmlEditor->IsSelectionEditable();
+  return htmlEditor->IsModifiable() && htmlEditor->IsSelectionEditable();
 }
 
 // corresponding STATE_ATTRIBUTE is: src (img) and href (a)
diff --git a/editor/libeditor/HTMLEditorDeleteHandler.cpp b/editor/libeditor/HTMLEditorDeleteHandler.cpp
index 18f9eda88e..39bb95151e 100644
--- a/editor/libeditor/HTMLEditorDeleteHandler.cpp
+++ b/editor/libeditor/HTMLEditorDeleteHandler.cpp
@@ -152,9 +152,20 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
       const Element& aEditingHost);
 
  private:
-  bool IsHandlingRecursively() const { return mParent != nullptr; }
+  [[nodiscard]] bool IsHandlingRecursively() const {
+    return mParent != nullptr;
+  }
 
-  bool CanFallbackToDeleteRangesWithTransaction(
+  [[nodiscard]] bool CanFallbackToDeleteRangeWithTransaction(
+      const nsRange& aRangeToDelete) const {
+    return !IsHandlingRecursively() &&
+           (!aRangeToDelete.Collapsed() ||
+            EditorBase::HowToHandleCollapsedRangeFor(
+                mOriginalDirectionAndAmount) !=
+                EditorBase::HowToHandleCollapsedRange::Ignore);
+  }
+
+  [[nodiscard]] bool CanFallbackToDeleteRangesWithTransaction(
       const AutoRangeArray& aRangesToDelete) const {
     return !IsHandlingRecursively() && !aRangesToDelete.Ranges().IsEmpty() &&
            (!aRangesToDelete.IsCollapsed() ||
@@ -405,6 +416,20 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
                                            const EditorDOMPoint& aPoint);
 
   [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<CaretPoint, nsresult>
+  FallbackToDeleteRangeWithTransaction(HTMLEditor& aHTMLEditor,
+                                       nsRange& aRangeToDelete) const {
+    MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
+    MOZ_ASSERT(CanFallbackToDeleteRangeWithTransaction(aRangeToDelete));
+    Result<CaretPoint, nsresult> caretPointOrError =
+        aHTMLEditor.DeleteRangeWithTransaction(mOriginalDirectionAndAmount,
+                                               mOriginalStripWrappers,
+                                               aRangeToDelete);
+    NS_WARNING_ASSERTION(caretPointOrError.isOk(),
+                         "EditorBase::DeleteRangeWithTransaction() failed");
+    return caretPointOrError;
+  }
+
+  [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<CaretPoint, nsresult>
   FallbackToDeleteRangesWithTransaction(HTMLEditor& aHTMLEditor,
                                         AutoRangeArray& aRangesToDelete) const {
     MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
@@ -414,26 +439,68 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
                                                 mOriginalStripWrappers,
                                                 aRangesToDelete);
     NS_WARNING_ASSERTION(caretPointOrError.isOk(),
-                         "HTMLEditor::DeleteRangesWithTransaction() failed");
+                         "EditorBase::DeleteRangesWithTransaction() failed");
     return caretPointOrError;
   }
 
   /**
-   * ComputeRangesToDeleteRangesWithTransaction() computes target ranges
-   * which will be called by `EditorBase::DeleteRangesWithTransaction()`.
+   * Compute target range(s) which will be called by
+   * `EditorBase::DeleteRangeWithTransaction()` or
+   * `EditorBase::DeleteRangesWithTransaction()`.
    * TODO: We should not use it for consistency with each deletion handler
    *       in this and nested classes.
    */
+  nsresult ComputeRangeToDeleteRangeWithTransaction(
+      const HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
+      nsRange& aRange, const Element& aEditingHost) const;
   nsresult ComputeRangesToDeleteRangesWithTransaction(
       const HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-      AutoRangeArray& aRangesToDelete) const;
+      AutoRangeArray& aRangesToDelete, const Element& aEditingHost) const {
+    MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+    const EditorBase::HowToHandleCollapsedRange howToHandleCollapsedRange =
+        EditorBase::HowToHandleCollapsedRangeFor(aDirectionAndAmount);
+    if (NS_WARN_IF(aRangesToDelete.IsCollapsed() &&
+                   howToHandleCollapsedRange ==
+                       EditorBase::HowToHandleCollapsedRange::Ignore)) {
+      return NS_ERROR_FAILURE;
+    }
 
+    for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+      if (range->Collapsed()) {
+        continue;
+      }
+      nsresult rv = ComputeRangeToDeleteRangeWithTransaction(
+          aHTMLEditor, aDirectionAndAmount, range, aEditingHost);
+      if (NS_FAILED(rv)) {
+        NS_WARNING(
+            "AutoDeleteRangesHandler::ComputeRangeToDeleteRangeWithTransaction("
+            ") failed");
+        return rv;
+      }
+    }
+    return NS_OK;
+  }
+
+  nsresult FallbackToComputeRangeToDeleteRangeWithTransaction(
+      const HTMLEditor& aHTMLEditor, nsRange& aRangeToDelete,
+      const Element& aEditingHost) const {
+    MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
+    MOZ_ASSERT(CanFallbackToDeleteRangeWithTransaction(aRangeToDelete));
+    nsresult rv = ComputeRangeToDeleteRangeWithTransaction(
+        aHTMLEditor, mOriginalDirectionAndAmount, aRangeToDelete, aEditingHost);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                         "AutoDeleteRangesHandler::"
+                         "ComputeRangeToDeleteRangeWithTransaction() failed");
+    return rv;
+  }
   nsresult FallbackToComputeRangesToDeleteRangesWithTransaction(
-      const HTMLEditor& aHTMLEditor, AutoRangeArray& aRangesToDelete) const {
+      const HTMLEditor& aHTMLEditor, AutoRangeArray& aRangesToDelete,
+      const Element& aEditingHost) const {
     MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
     MOZ_ASSERT(CanFallbackToDeleteRangesWithTransaction(aRangesToDelete));
     nsresult rv = ComputeRangesToDeleteRangesWithTransaction(
-        aHTMLEditor, mOriginalDirectionAndAmount, aRangesToDelete);
+        aHTMLEditor, mOriginalDirectionAndAmount, aRangesToDelete,
+        aEditingHost);
     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                          "AutoDeleteRangesHandler::"
                          "ComputeRangesToDeleteRangesWithTransaction() failed");
@@ -493,18 +560,18 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
         const WSRunScanner& aWSRunScannerAtCaret);
 
     /**
-     * PrepareToDeleteNonCollapsedRanges() considers left block element and
+     * PrepareToDeleteNonCollapsedRange() considers left block element and
      * right block element which are inclusive ancestor block element of
-     * start and end container of first range of aRangesToDelete.
+     * start and end container of aRangeToDelete
      *
      * @param aHTMLEditor               The HTML editor.
-     * @param aRangesToDelete           Ranges to delete.  Must not be
+     * @param aRangeToDelete            The range to delete.  Must not be
      *                                  collapsed.
      * @return                          true if can continue to handle the
      *                                  deletion.
      */
-    bool PrepareToDeleteNonCollapsedRanges(
-        const HTMLEditor& aHTMLEditor, const AutoRangeArray& aRangesToDelete);
+    bool PrepareToDeleteNonCollapsedRange(const HTMLEditor& aHTMLEditor,
+                                          const nsRange& aRangeToDelete);
 
     /**
      * Run() executes the joining.
@@ -514,14 +581,13 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
      * @param aStripWrappers            Must be eStrip or eNoStrip.
      * @param aCaretPoint               The caret point (i.e., selection start
      *                                  or end).
-     * @param aRangesToDelete           Ranges to delete of the caller.
-     *                                  This should be collapsed and match
-     *                                  with aCaretPoint.
+     * @param aRangeToDelete            The range to delete.  This should be
+     *                                  collapsed and match with aCaretPoint.
      */
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult> Run(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
         nsIEditor::EStripWrappers aStripWrappers,
-        const EditorDOMPoint& aCaretPoint, AutoRangeArray& aRangesToDelete,
+        const EditorDOMPoint& aCaretPoint, nsRange& aRangeToDelete,
         const Element& aEditingHost) {
       switch (mMode) {
         case Mode::JoinCurrentBlock: {
@@ -537,7 +603,7 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
           Result<EditActionResult, nsresult> result =
               HandleDeleteAtOtherBlockBoundary(aHTMLEditor, aDirectionAndAmount,
                                                aStripWrappers, aCaretPoint,
-                                               aRangesToDelete, aEditingHost);
+                                               aRangeToDelete, aEditingHost);
           NS_WARNING_ASSERTION(result.isOk(),
                                "AutoBlockElementsJoiner::"
                                "HandleDeleteAtOtherBlockBoundary() failed");
@@ -552,8 +618,8 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
           return result;
         }
         case Mode::JoinBlocksInSameParent:
-        case Mode::DeleteContentInRanges:
-        case Mode::DeleteNonCollapsedRanges:
+        case Mode::DeleteContentInRange:
+        case Mode::DeleteNonCollapsedRange:
           MOZ_ASSERT_UNREACHABLE(
               "This mode should be handled in the other Run()");
           return Err(NS_ERROR_UNEXPECTED);
@@ -563,41 +629,41 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
       return Err(NS_ERROR_NOT_INITIALIZED);
     }
 
-    nsresult ComputeRangesToDelete(const HTMLEditor& aHTMLEditor,
-                                   nsIEditor::EDirection aDirectionAndAmount,
-                                   const EditorDOMPoint& aCaretPoint,
-                                   AutoRangeArray& aRangesToDelete,
-                                   const Element& aEditingHost) const {
+    nsresult ComputeRangeToDelete(const HTMLEditor& aHTMLEditor,
+                                  nsIEditor::EDirection aDirectionAndAmount,
+                                  const EditorDOMPoint& aCaretPoint,
+                                  nsRange& aRangeToDelete,
+                                  const Element& aEditingHost) const {
       switch (mMode) {
         case Mode::JoinCurrentBlock: {
-          nsresult rv = ComputeRangesToDeleteAtCurrentBlockBoundary(
-              aHTMLEditor, aCaretPoint, aRangesToDelete, aEditingHost);
+          nsresult rv = ComputeRangeToDeleteAtCurrentBlockBoundary(
+              aHTMLEditor, aCaretPoint, aRangeToDelete, aEditingHost);
           NS_WARNING_ASSERTION(
               NS_SUCCEEDED(rv),
               "AutoBlockElementsJoiner::"
-              "ComputeRangesToDeleteAtCurrentBlockBoundary() failed");
+              "ComputeRangeToDeleteAtCurrentBlockBoundary() failed");
           return rv;
         }
         case Mode::JoinOtherBlock: {
-          nsresult rv = ComputeRangesToDeleteAtOtherBlockBoundary(
-              aHTMLEditor, aDirectionAndAmount, aCaretPoint, aRangesToDelete,
+          nsresult rv = ComputeRangeToDeleteAtOtherBlockBoundary(
+              aHTMLEditor, aDirectionAndAmount, aCaretPoint, aRangeToDelete,
               aEditingHost);
           NS_WARNING_ASSERTION(
               NS_SUCCEEDED(rv),
               "AutoBlockElementsJoiner::"
-              "ComputeRangesToDeleteAtOtherBlockBoundary() failed");
+              "ComputeRangeToDeleteAtOtherBlockBoundary() failed");
           return rv;
         }
         case Mode::DeleteBRElement: {
-          nsresult rv = ComputeRangesToDeleteBRElement(aRangesToDelete);
+          nsresult rv = ComputeRangeToDeleteBRElement(aRangeToDelete);
           NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                                "AutoBlockElementsJoiner::"
-                               "ComputeRangesToDeleteBRElement() failed");
+                               "ComputeRangeToDeleteBRElement() failed");
           return rv;
         }
         case Mode::JoinBlocksInSameParent:
-        case Mode::DeleteContentInRanges:
-        case Mode::DeleteNonCollapsedRanges:
+        case Mode::DeleteContentInRange:
+        case Mode::DeleteNonCollapsedRange:
           MOZ_ASSERT_UNREACHABLE(
               "This mode should be handled in the other "
               "ComputeRangesToDelete()");
@@ -615,7 +681,7 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
      * @param aDirectionAndAmount       Direction of the deletion.
      * @param aStripWrappers            Whether delete or keep new empty
      *                                  ancestor elements.
-     * @param aRangesToDelete           Ranges to delete.  Must not be
+     * @param aRangeToDelete            The range to delete.  Must not be
      *                                  collapsed.
      * @param aSelectionWasCollapsed    Whether selection was or was not
      *                                  collapsed when starting to handle
@@ -623,8 +689,7 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
      */
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult> Run(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-        nsIEditor::EStripWrappers aStripWrappers,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost) {
       switch (mMode) {
@@ -638,26 +703,25 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
           Result<EditActionResult, nsresult> result =
               JoinBlockElementsInSameParent(
                   aHTMLEditor, aDirectionAndAmount, aStripWrappers,
-                  aRangesToDelete, aSelectionWasCollapsed, aEditingHost);
+                  aRangeToDelete, aSelectionWasCollapsed, aEditingHost);
           NS_WARNING_ASSERTION(result.isOk(),
                                "AutoBlockElementsJoiner::"
                                "JoinBlockElementsInSameParent() failed");
           return result;
         }
-        case Mode::DeleteContentInRanges: {
-          Result<EditActionResult, nsresult> result =
-              DeleteContentInRanges(aHTMLEditor, aDirectionAndAmount,
-                                    aStripWrappers, aRangesToDelete);
+        case Mode::DeleteContentInRange: {
+          Result<EditActionResult, nsresult> result = DeleteContentInRange(
+              aHTMLEditor, aDirectionAndAmount, aStripWrappers, aRangeToDelete);
           NS_WARNING_ASSERTION(
               result.isOk(),
-              "AutoBlockElementsJoiner::DeleteContentInRanges() failed");
+              "AutoBlockElementsJoiner::DeleteContentInRange() failed");
           return result;
         }
-        case Mode::DeleteNonCollapsedRanges: {
+        case Mode::DeleteNonCollapsedRange: {
           Result<EditActionResult, nsresult> result =
-              HandleDeleteNonCollapsedRanges(
+              HandleDeleteNonCollapsedRange(
                   aHTMLEditor, aDirectionAndAmount, aStripWrappers,
-                  aRangesToDelete, aSelectionWasCollapsed, aEditingHost);
+                  aRangeToDelete, aSelectionWasCollapsed, aEditingHost);
           NS_WARNING_ASSERTION(result.isOk(),
                                "AutoBlockElementsJoiner::"
                                "HandleDeleteNonCollapsedRange() failed");
@@ -671,10 +735,9 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
       return Err(NS_ERROR_NOT_INITIALIZED);
     }
 
-    nsresult ComputeRangesToDelete(
+    nsresult ComputeRangeToDelete(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost) const {
       switch (mMode) {
@@ -686,25 +749,25 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
               "ComputeRangesToDelete()");
           return NS_ERROR_UNEXPECTED;
         case Mode::JoinBlocksInSameParent: {
-          nsresult rv = ComputeRangesToJoinBlockElementsInSameParent(
-              aHTMLEditor, aDirectionAndAmount, aRangesToDelete);
+          nsresult rv = ComputeRangeToJoinBlockElementsInSameParent(
+              aHTMLEditor, aDirectionAndAmount, aRangeToDelete, aEditingHost);
           NS_WARNING_ASSERTION(
               NS_SUCCEEDED(rv),
               "AutoBlockElementsJoiner::"
               "ComputeRangesToJoinBlockElementsInSameParent() failed");
           return rv;
         }
-        case Mode::DeleteContentInRanges: {
-          nsresult rv = ComputeRangesToDeleteContentInRanges(
-              aHTMLEditor, aDirectionAndAmount, aRangesToDelete);
+        case Mode::DeleteContentInRange: {
+          nsresult rv = ComputeRangeToDeleteContentInRange(
+              aHTMLEditor, aDirectionAndAmount, aRangeToDelete, aEditingHost);
           NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                                "AutoBlockElementsJoiner::"
                                "ComputeRangesToDeleteContentInRanges() failed");
           return rv;
         }
-        case Mode::DeleteNonCollapsedRanges: {
-          nsresult rv = ComputeRangesToDeleteNonCollapsedRanges(
-              aHTMLEditor, aDirectionAndAmount, aRangesToDelete,
+        case Mode::DeleteNonCollapsedRange: {
+          nsresult rv = ComputeRangeToDeleteNonCollapsedRange(
+              aHTMLEditor, aDirectionAndAmount, aRangeToDelete,
               aSelectionWasCollapsed, aEditingHost);
           NS_WARNING_ASSERTION(
               NS_SUCCEEDED(rv),
@@ -731,63 +794,59 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
     HandleDeleteAtCurrentBlockBoundary(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
         const EditorDOMPoint& aCaretPoint, const Element& aEditingHost);
-    nsresult ComputeRangesToDeleteAtCurrentBlockBoundary(
+    nsresult ComputeRangeToDeleteAtCurrentBlockBoundary(
         const HTMLEditor& aHTMLEditor, const EditorDOMPoint& aCaretPoint,
-        AutoRangeArray& aRangesToDelete, const Element& aEditingHost) const;
+        nsRange& aRangeToDelete, const Element& aEditingHost) const;
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult>
     HandleDeleteAtOtherBlockBoundary(HTMLEditor& aHTMLEditor,
                                      nsIEditor::EDirection aDirectionAndAmount,
                                      nsIEditor::EStripWrappers aStripWrappers,
                                      const EditorDOMPoint& aCaretPoint,
-                                     AutoRangeArray& aRangesToDelete,
+                                     nsRange& aRangeToDelete,
                                      const Element& aEditingHost);
     // FYI: This method may modify selection, but it won't cause running
     //      script because of `AutoHideSelectionChanges` which blocks
     //      selection change listeners and the selection change event
     //      dispatcher.
     MOZ_CAN_RUN_SCRIPT_BOUNDARY nsresult
-    ComputeRangesToDeleteAtOtherBlockBoundary(
+    ComputeRangeToDeleteAtOtherBlockBoundary(
         const HTMLEditor& aHTMLEditor,
         nsIEditor::EDirection aDirectionAndAmount,
-        const EditorDOMPoint& aCaretPoint, AutoRangeArray& aRangesToDelete,
+        const EditorDOMPoint& aCaretPoint, nsRange& aRangeToDelete,
         const Element& aEditingHost) const;
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult>
     JoinBlockElementsInSameParent(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-        nsIEditor::EStripWrappers aStripWrappers,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost);
-    nsresult ComputeRangesToJoinBlockElementsInSameParent(
+    nsresult ComputeRangeToJoinBlockElementsInSameParent(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete) const;
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRangeToDelete,
+        const Element& aEditingHost) const;
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult>
     DeleteBRElement(HTMLEditor& aHTMLEditor,
                     nsIEditor::EDirection aDirectionAndAmount,
                     const Element& aEditingHost);
-    nsresult ComputeRangesToDeleteBRElement(
-        AutoRangeArray& aRangesToDelete) const;
+    nsresult ComputeRangeToDeleteBRElement(nsRange& aRangeToDelete) const;
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult>
-    DeleteContentInRanges(HTMLEditor& aHTMLEditor,
-                          nsIEditor::EDirection aDirectionAndAmount,
-                          nsIEditor::EStripWrappers aStripWrappers,
-                          AutoRangeArray& aRangesToDelete);
-    nsresult ComputeRangesToDeleteContentInRanges(
+    DeleteContentInRange(HTMLEditor& aHTMLEditor,
+                         nsIEditor::EDirection aDirectionAndAmount,
+                         nsIEditor::EStripWrappers aStripWrappers,
+                         nsRange& aRangeToDelete);
+    nsresult ComputeRangeToDeleteContentInRange(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete) const;
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRange,
+        const Element& aEditingHost) const;
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT Result<EditActionResult, nsresult>
-    HandleDeleteNonCollapsedRanges(
+    HandleDeleteNonCollapsedRange(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-        nsIEditor::EStripWrappers aStripWrappers,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost);
-    nsresult ComputeRangesToDeleteNonCollapsedRanges(
+    nsresult ComputeRangeToDeleteNonCollapsedRange(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost) const;
 
@@ -829,7 +888,7 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed)
         const;
     Result<bool, nsresult>
-    ComputeRangesToDeleteNodesEntirelyInRangeButKeepTableStructure(
+    ComputeRangeToDeleteNodesEntirelyInRangeButKeepTableStructure(
         const HTMLEditor& aHTMLEditor, nsRange& aRange,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed)
         const;
@@ -900,17 +959,17 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
       }
 
       /**
-       * ComputeRangesToDelete() extends aRangesToDelete includes the element
+       * ComputeRangesToDelete() extends aRangeToDelete includes the element
        * boundaries between joining blocks.  If they won't be joined, this
        * collapses the range to aCaretPoint.
        */
-      nsresult ComputeRangesToDelete(const HTMLEditor& aHTMLEditor,
-                                     const EditorDOMPoint& aCaretPoint,
-                                     AutoRangeArray& aRangesToDelete) const;
+      nsresult ComputeRangeToDelete(const HTMLEditor& aHTMLEditor,
+                                    const EditorDOMPoint& aCaretPoint,
+                                    nsRange& aRangeToDelete) const;
 
       /**
        * Join inclusive ancestor block elements which are found by preceding
-       * Preare() call.
+       * Prepare() call.
        * The right element is always joined to the left element.
        * If the elements are the same type and not nested within each other,
        * JoinEditableNodesWithTransaction() is called (example, joining two
@@ -971,8 +1030,8 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
       JoinOtherBlock,
       JoinBlocksInSameParent,
       DeleteBRElement,
-      DeleteContentInRanges,
-      DeleteNonCollapsedRanges,
+      DeleteContentInRange,
+      DeleteNonCollapsedRange,
     };
     AutoDeleteRangesHandler* mDeleteRangesHandler;
     const AutoDeleteRangesHandler& mDeleteRangesHandlerConst;
@@ -1291,7 +1350,7 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDelete(
         return NS_SUCCESS_DOM_NO_OPERATION;
       }
       nsresult rv = FallbackToComputeRangesToDeleteRangesWithTransaction(
-          aHTMLEditor, aRangesToDelete);
+          aHTMLEditor, aRangesToDelete, *editingHost);
       NS_WARNING_ASSERTION(
           NS_SUCCEEDED(rv),
           "AutoDeleteRangesHandler::"
@@ -1770,40 +1829,57 @@ HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDeleteAroundCollapsedRanges(
     if (NS_WARN_IF(!aScanFromCaretPointResult.GetContent()->IsElement())) {
       return NS_ERROR_FAILURE;
     }
-    AutoBlockElementsJoiner joiner(*this);
-    if (!joiner.PrepareToDeleteAtOtherBlockBoundary(
-            aHTMLEditor, aDirectionAndAmount,
-            *aScanFromCaretPointResult.ElementPtr(),
-            aWSRunScannerAtCaret.ScanStartRef(), aWSRunScannerAtCaret)) {
-      return NS_SUCCESS_DOM_NO_OPERATION;
+    MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+    bool handled = false;
+    for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+      MOZ_ASSERT(range->IsPositioned());
+      AutoBlockElementsJoiner joiner(*this);
+      if (!joiner.PrepareToDeleteAtOtherBlockBoundary(
+              aHTMLEditor, aDirectionAndAmount,
+              *aScanFromCaretPointResult.ElementPtr(),
+              aWSRunScannerAtCaret.ScanStartRef(), aWSRunScannerAtCaret)) {
+        continue;
+      }
+      handled = true;
+      nsresult rv = joiner.ComputeRangeToDelete(
+          aHTMLEditor, aDirectionAndAmount, aWSRunScannerAtCaret.ScanStartRef(),
+          range, aEditingHost);
+      if (NS_FAILED(rv)) {
+        NS_WARNING(
+            "AutoBlockElementsJoiner::ComputeRangeToDelete() failed (other "
+            "block boundary)");
+        return rv;
+      }
     }
-    nsresult rv = joiner.ComputeRangesToDelete(
-        aHTMLEditor, aDirectionAndAmount, aWSRunScannerAtCaret.ScanStartRef(),
-        aRangesToDelete, aEditingHost);
-    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
-                         "AutoBlockElementsJoiner::ComputeRangesToDelete() "
-                         "failed (other block boundary)");
-    return rv;
+    return handled ? NS_OK : NS_SUCCESS_DOM_NO_OPERATION;
   }
 
   if (aScanFromCaretPointResult.ReachedCurrentBlockBoundary()) {
     if (NS_WARN_IF(!aScanFromCaretPointResult.GetContent()->IsElement())) {
       return NS_ERROR_FAILURE;
     }
-    AutoBlockElementsJoiner joiner(*this);
-    if (!joiner.PrepareToDeleteAtCurrentBlockBoundary(
-            aHTMLEditor, aDirectionAndAmount,
-            *aScanFromCaretPointResult.ElementPtr(),
-            aWSRunScannerAtCaret.ScanStartRef())) {
-      return NS_SUCCESS_DOM_NO_OPERATION;
+    MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+    bool handled = false;
+    for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+      AutoBlockElementsJoiner joiner(*this);
+      if (!joiner.PrepareToDeleteAtCurrentBlockBoundary(
+              aHTMLEditor, aDirectionAndAmount,
+              *aScanFromCaretPointResult.ElementPtr(),
+              aWSRunScannerAtCaret.ScanStartRef())) {
+        continue;
+      }
+      handled = true;
+      nsresult rv = joiner.ComputeRangeToDelete(
+          aHTMLEditor, aDirectionAndAmount, aWSRunScannerAtCaret.ScanStartRef(),
+          range, aEditingHost);
+      if (NS_FAILED(rv)) {
+        NS_WARNING(
+            "AutoBlockElementsJoiner::ComputeRangeToDelete() failed (current "
+            "block boundary)");
+        return rv;
+      }
     }
-    nsresult rv = joiner.ComputeRangesToDelete(
-        aHTMLEditor, aDirectionAndAmount, aWSRunScannerAtCaret.ScanStartRef(),
-        aRangesToDelete, aEditingHost);
-    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
-                         "AutoBlockElementsJoiner::ComputeRangesToDelete() "
-                         "failed (current block boundary)");
-    return rv;
+    return handled ? NS_OK : NS_SUCCESS_DOM_NO_OPERATION;
   }
 
   return NS_OK;
@@ -1946,40 +2022,62 @@ HTMLEditor::AutoDeleteRangesHandler::HandleDeleteAroundCollapsedRanges(
     if (NS_WARN_IF(!aScanFromCaretPointResult.GetContent()->IsElement())) {
       return Err(NS_ERROR_FAILURE);
     }
-    AutoBlockElementsJoiner joiner(*this);
-    if (!joiner.PrepareToDeleteAtOtherBlockBoundary(
-            aHTMLEditor, aDirectionAndAmount,
-            *aScanFromCaretPointResult.ElementPtr(),
-            aWSRunScannerAtCaret.ScanStartRef(), aWSRunScannerAtCaret)) {
-      return EditActionResult::CanceledResult();
+    MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+    bool allRangesNotHandled = true;
+    auto ret = EditActionResult::IgnoredResult();
+    for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+      AutoBlockElementsJoiner joiner(*this);
+      if (!joiner.PrepareToDeleteAtOtherBlockBoundary(
+              aHTMLEditor, aDirectionAndAmount,
+              *aScanFromCaretPointResult.ElementPtr(),
+              aWSRunScannerAtCaret.ScanStartRef(), aWSRunScannerAtCaret)) {
+        continue;
+      }
+      allRangesNotHandled = false;
+      Result<EditActionResult, nsresult> result =
+          joiner.Run(aHTMLEditor, aDirectionAndAmount, aStripWrappers,
+                     aWSRunScannerAtCaret.ScanStartRef(), MOZ_KnownLive(range),
+                     aEditingHost);
+      if (MOZ_UNLIKELY(result.isErr())) {
+        NS_WARNING(
+            "AutoBlockElementsJoiner::Run() failed (other block boundary)");
+        return result;
+      }
+      ret |= result.inspect();
     }
-    Result<EditActionResult, nsresult> result = joiner.Run(
-        aHTMLEditor, aDirectionAndAmount, aStripWrappers,
-        aWSRunScannerAtCaret.ScanStartRef(), aRangesToDelete, aEditingHost);
-    NS_WARNING_ASSERTION(
-        result.isOk(),
-        "AutoBlockElementsJoiner::Run() failed (other block boundary)");
-    return result;
+    return allRangesNotHandled ? EditActionResult::CanceledResult()
+                               : std::move(ret);
   }
 
   if (aScanFromCaretPointResult.ReachedCurrentBlockBoundary()) {
     if (NS_WARN_IF(!aScanFromCaretPointResult.GetContent()->IsElement())) {
       return Err(NS_ERROR_FAILURE);
     }
-    AutoBlockElementsJoiner joiner(*this);
-    if (!joiner.PrepareToDeleteAtCurrentBlockBoundary(
-            aHTMLEditor, aDirectionAndAmount,
-            *aScanFromCaretPointResult.ElementPtr(),
-            aWSRunScannerAtCaret.ScanStartRef())) {
-      return EditActionResult::CanceledResult();
+    MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+    bool allRangesNotHandled = true;
+    auto ret = EditActionResult::IgnoredResult();
+    for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+      AutoBlockElementsJoiner joiner(*this);
+      if (!joiner.PrepareToDeleteAtCurrentBlockBoundary(
+              aHTMLEditor, aDirectionAndAmount,
+              *aScanFromCaretPointResult.ElementPtr(),
+              aWSRunScannerAtCaret.ScanStartRef())) {
+        continue;
+      }
+      allRangesNotHandled = false;
+      Result<EditActionResult, nsresult> result =
+          joiner.Run(aHTMLEditor, aDirectionAndAmount, aStripWrappers,
+                     aWSRunScannerAtCaret.ScanStartRef(), MOZ_KnownLive(range),
+                     aEditingHost);
+      if (MOZ_UNLIKELY(result.isErr())) {
+        NS_WARNING(
+            "AutoBlockElementsJoiner::Run() failed (current block boundary)");
+        return result;
+      }
+      ret |= result.inspect();
     }
-    Result<EditActionResult, nsresult> result = joiner.Run(
-        aHTMLEditor, aDirectionAndAmount, aStripWrappers,
-        aWSRunScannerAtCaret.ScanStartRef(), aRangesToDelete, aEditingHost);
-    NS_WARNING_ASSERTION(
-        result.isOk(),
-        "AutoBlockElementsJoiner::Run() failed (current block boundary)");
-    return result;
+    return allRangesNotHandled ? EditActionResult::CanceledResult()
+                               : std::move(ret);
   }
 
   MOZ_ASSERT_UNREACHABLE("New type of reached content hasn't been handled yet");
@@ -2439,13 +2537,14 @@ bool HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToDeleteBRElement(AutoRangeArray& aRangesToDelete) const {
+    ComputeRangeToDeleteBRElement(nsRange& aRangeToDelete) const {
   MOZ_ASSERT(mBRElement);
   // XXX Why don't we scan invisible leading white-spaces which follows the
   //     `<br>` element?
-  nsresult rv = aRangesToDelete.SelectNode(*mBRElement);
-  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "AutoRangeArray::SelectNode() failed");
-  return rv;
+  IgnoredErrorResult error;
+  aRangeToDelete.SelectNode(*mBRElement, error);
+  NS_WARNING_ASSERTION(!error.Failed(), "nsRange::SelectNode() failed");
+  return error.StealNSResult();
 }
 
 Result<EditActionResult, nsresult>
@@ -2545,10 +2644,10 @@ HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::DeleteBRElement(
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToDeleteAtOtherBlockBoundary(
+    ComputeRangeToDeleteAtOtherBlockBoundary(
         const HTMLEditor& aHTMLEditor,
         nsIEditor::EDirection aDirectionAndAmount,
-        const EditorDOMPoint& aCaretPoint, AutoRangeArray& aRangesToDelete,
+        const EditorDOMPoint& aCaretPoint, nsRange& aRangeToDelete,
         const Element& aEditingHost) const {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
   MOZ_ASSERT(aCaretPoint.IsSetAndValid());
@@ -2557,20 +2656,19 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
 
   if (HTMLEditUtils::GetInclusiveAncestorAnyTableElement(*mLeftContent) !=
       HTMLEditUtils::GetInclusiveAncestorAnyTableElement(*mRightContent)) {
-    if (!mDeleteRangesHandlerConst.CanFallbackToDeleteRangesWithTransaction(
-            aRangesToDelete)) {
-      nsresult rv = aRangesToDelete.Collapse(aCaretPoint);
-      NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
-                           "AutoRangeArray::Collapse() failed");
+    if (!mDeleteRangesHandlerConst.CanFallbackToDeleteRangeWithTransaction(
+            aRangeToDelete)) {
+      nsresult rv = aRangeToDelete.CollapseTo(aCaretPoint.ToRawRangeBoundary());
+      NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "nsRange::CollapseTo() failed");
       return rv;
     }
     nsresult rv = mDeleteRangesHandlerConst
-                      .FallbackToComputeRangesToDeleteRangesWithTransaction(
-                          aHTMLEditor, aRangesToDelete);
+                      .FallbackToComputeRangeToDeleteRangeWithTransaction(
+                          aHTMLEditor, aRangeToDelete, aEditingHost);
     NS_WARNING_ASSERTION(
         NS_SUCCEEDED(rv),
         "AutoDeleteRangesHandler::"
-        "FallbackToComputeRangesToDeleteRangesWithTransaction() failed");
+        "FallbackToComputeRangeToDeleteRangeWithTransaction() failed");
     return rv;
   }
 
@@ -2585,11 +2683,10 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
   if (canJoinThem.inspect() && joiner.CanJoinBlocks() &&
       !joiner.ShouldDeleteLeafContentInstead()) {
     nsresult rv =
-        joiner.ComputeRangesToDelete(aHTMLEditor, aCaretPoint, aRangesToDelete);
-    NS_WARNING_ASSERTION(
-        NS_SUCCEEDED(rv),
-        "AutoInclusiveAncestorBlockElementsJoiner::ComputeRangesToDelete() "
-        "failed");
+        joiner.ComputeRangeToDelete(aHTMLEditor, aCaretPoint, aRangeToDelete);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+                         "AutoInclusiveAncestorBlockElementsJoiner::"
+                         "ComputeRangeToDelete() failed");
     return rv;
   }
 
@@ -2612,11 +2709,11 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
           : EditorRawDOMPoint(mLeafContentInOtherBlock, 0);
   // If new caret position is same as current caret position, we can do
   // nothing anymore.
-  if (aRangesToDelete.IsCollapsed() &&
-      aRangesToDelete.FocusRef() == newCaretPoint.ToRawRangeBoundary()) {
+  if (aRangeToDelete.Collapsed() &&
+      aRangeToDelete.EndRef() == newCaretPoint.ToRawRangeBoundary()) {
     return NS_OK;
   }
-  // TODO: Stop modifying the `Selection` for computing the targer ranges.
+  // TODO: Stop modifying the `Selection` for computing the target ranges.
   nsresult rv = aHTMLEditor.CollapseSelectionTo(newCaretPoint);
   if (MOZ_UNLIKELY(rv == NS_ERROR_EDITOR_DESTROYED)) {
     NS_WARNING(
@@ -2626,13 +2723,25 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                        "EditorBase::CollapseSelectionTo() failed");
   if (NS_SUCCEEDED(rv)) {
-    aRangesToDelete.Initialize(aHTMLEditor.SelectionRef());
+    AutoRangeArray rangeArray(aHTMLEditor.SelectionRef());
     AutoDeleteRangesHandler anotherHandler(mDeleteRangesHandlerConst);
     rv = anotherHandler.ComputeRangesToDelete(aHTMLEditor, aDirectionAndAmount,
-                                              aRangesToDelete, aEditingHost);
-    NS_WARNING_ASSERTION(
-        NS_SUCCEEDED(rv),
-        "Recursive AutoDeleteRangesHandler::ComputeRangesToDelete() failed");
+                                              rangeArray, aEditingHost);
+    if (NS_SUCCEEDED(rv)) {
+      if (MOZ_LIKELY(!rangeArray.Ranges().IsEmpty())) {
+        MOZ_ASSERT(rangeArray.Ranges().Length() == 1);
+        aRangeToDelete.SetStartAndEnd(rangeArray.FirstRangeRef()->StartRef(),
+                                      rangeArray.FirstRangeRef()->EndRef());
+      } else {
+        NS_WARNING(
+            "Recursive AutoDeleteRangesHandler::ComputeRangesToDelete() "
+            "returned no range");
+        rv = NS_ERROR_FAILURE;
+      }
+    } else {
+      NS_WARNING(
+          "Recursive AutoDeleteRangesHandler::ComputeRangesToDelete() failed");
+    }
   }
   // Restore selection.
   nsresult rvCollapsingSelectionTo =
@@ -2654,7 +2763,7 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
     AutoBlockElementsJoiner::HandleDeleteAtOtherBlockBoundary(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
         nsIEditor::EStripWrappers aStripWrappers,
-        const EditorDOMPoint& aCaretPoint, AutoRangeArray& aRangesToDelete,
+        const EditorDOMPoint& aCaretPoint, nsRange& aRangeToDelete,
         const Element& aEditingHost) {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
   MOZ_ASSERT(aCaretPoint.IsSetAndValid());
@@ -2666,13 +2775,13 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
       HTMLEditUtils::GetInclusiveAncestorAnyTableElement(*mRightContent)) {
     // If we have not deleted `<br>` element and are not called recursively,
     // we should call `DeleteRangesWithTransaction()` here.
-    if (!mDeleteRangesHandler->CanFallbackToDeleteRangesWithTransaction(
-            aRangesToDelete)) {
+    if (!mDeleteRangesHandler->CanFallbackToDeleteRangeWithTransaction(
+            aRangeToDelete)) {
       return EditActionResult::IgnoredResult();
     }
     Result<CaretPoint, nsresult> caretPointOrError =
-        mDeleteRangesHandler->FallbackToDeleteRangesWithTransaction(
-            aHTMLEditor, aRangesToDelete);
+        mDeleteRangesHandler->FallbackToDeleteRangeWithTransaction(
+            aHTMLEditor, aRangeToDelete);
     if (MOZ_UNLIKELY(caretPointOrError.isErr())) {
       NS_WARNING(
           "AutoDeleteRangesHandler::FallbackToDeleteRangesWithTransaction() "
@@ -2789,8 +2898,8 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
               : EditorRawDOMPoint(mLeafContentInOtherBlock, 0);
       // If new caret position is same as current caret position, we can do
       // nothing anymore.
-      if (aRangesToDelete.IsCollapsed() &&
-          aRangesToDelete.FocusRef() == newCaretPoint.ToRawRangeBoundary()) {
+      if (aRangeToDelete.Collapsed() &&
+          aRangeToDelete.EndRef() == newCaretPoint.ToRawRangeBoundary()) {
         return EditActionResult::CanceledResult();
       }
       nsresult rv = aHTMLEditor.CollapseSelectionTo(newCaretPoint);
@@ -2945,9 +3054,9 @@ bool HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToDeleteAtCurrentBlockBoundary(
+    ComputeRangeToDeleteAtCurrentBlockBoundary(
         const HTMLEditor& aHTMLEditor, const EditorDOMPoint& aCaretPoint,
-        AutoRangeArray& aRangesToDelete, const Element& aEditingHost) const {
+        nsRange& aRangeToDelete, const Element& aEditingHost) const {
   MOZ_ASSERT(mLeftContent);
   MOZ_ASSERT(mRightContent);
 
@@ -2961,7 +3070,7 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
   }
   if (canJoinThem.inspect()) {
     nsresult rv =
-        joiner.ComputeRangesToDelete(aHTMLEditor, aCaretPoint, aRangesToDelete);
+        joiner.ComputeRangeToDelete(aHTMLEditor, aCaretPoint, aRangeToDelete);
     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                          "AutoInclusiveAncestorBlockElementsJoiner::"
                          "ComputeRangesToDelete() failed");
@@ -2970,8 +3079,8 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
 
   // In this case, nothing will be deleted so that the affected range should
   // be collapsed.
-  nsresult rv = aRangesToDelete.Collapse(aCaretPoint);
-  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "AutoRangeArray::Collapse() failed");
+  nsresult rv = aRangeToDelete.CollapseTo(aCaretPoint.ToRawRangeBoundary());
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "nsRange::CollapseTo() failed");
   return rv;
 }
 
@@ -3145,7 +3254,7 @@ HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDeleteNonCollapsedRanges(
       aRangesToDelete.FirstRangeRef()->GetEndContainer()) {
     if (!aRangesToDelete.FirstRangeRef()->Collapsed()) {
       nsresult rv = ComputeRangesToDeleteRangesWithTransaction(
-          aHTMLEditor, aDirectionAndAmount, aRangesToDelete);
+          aHTMLEditor, aDirectionAndAmount, aRangesToDelete, aEditingHost);
       NS_WARNING_ASSERTION(
           NS_SUCCEEDED(rv),
           "AutoDeleteRangesHandler::ComputeRangesToDeleteRangesWithTransaction("
@@ -3169,17 +3278,23 @@ HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDeleteNonCollapsedRanges(
     aDirectionAndAmount = nsIEditor::ePrevious;
   }
 
-  AutoBlockElementsJoiner joiner(*this);
-  if (!joiner.PrepareToDeleteNonCollapsedRanges(aHTMLEditor, aRangesToDelete)) {
-    return NS_ERROR_FAILURE;
+  for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+    if (MOZ_UNLIKELY(range->Collapsed())) {
+      continue;
+    }
+    AutoBlockElementsJoiner joiner(*this);
+    if (!joiner.PrepareToDeleteNonCollapsedRange(aHTMLEditor, range)) {
+      return NS_ERROR_FAILURE;
+    }
+    nsresult rv =
+        joiner.ComputeRangeToDelete(aHTMLEditor, aDirectionAndAmount, range,
+                                    aSelectionWasCollapsed, aEditingHost);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("AutoBlockElementsJoiner::ComputeRangeToDelete() failed");
+      return rv;
+    }
   }
-  nsresult rv = joiner.ComputeRangesToDelete(
-      aHTMLEditor, aDirectionAndAmount, aRangesToDelete, aSelectionWasCollapsed,
-      aEditingHost);
-  NS_WARNING_ASSERTION(
-      NS_SUCCEEDED(rv),
-      "AutoBlockElementsJoiner::ComputeRangesToDelete() failed");
-  return rv;
+  return NS_OK;
 }
 
 Result<EditActionResult, nsresult>
@@ -3351,29 +3466,40 @@ HTMLEditor::AutoDeleteRangesHandler::HandleDeleteNonCollapsedRanges(
     aDirectionAndAmount = nsIEditor::ePrevious;
   }
 
-  AutoBlockElementsJoiner joiner(*this);
-  if (!joiner.PrepareToDeleteNonCollapsedRanges(aHTMLEditor, aRangesToDelete)) {
-    return Err(NS_ERROR_FAILURE);
+  MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+  auto ret = EditActionResult::IgnoredResult();
+  for (const OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
+    if (MOZ_UNLIKELY(range->Collapsed())) {
+      continue;
+    }
+    AutoBlockElementsJoiner joiner(*this);
+    if (!joiner.PrepareToDeleteNonCollapsedRange(aHTMLEditor, range)) {
+      return Err(NS_ERROR_FAILURE);
+    }
+    Result<EditActionResult, nsresult> result =
+        joiner.Run(aHTMLEditor, aDirectionAndAmount, aStripWrappers,
+                   MOZ_KnownLive(range), aSelectionWasCollapsed, aEditingHost);
+    if (MOZ_UNLIKELY(result.isErr())) {
+      NS_WARNING("AutoBlockElementsJoiner::Run() failed");
+      return result;
+    }
+    ret |= result.inspect();
   }
-  Result<EditActionResult, nsresult> result =
-      joiner.Run(aHTMLEditor, aDirectionAndAmount, aStripWrappers,
-                 aRangesToDelete, aSelectionWasCollapsed, aEditingHost);
-  NS_WARNING_ASSERTION(result.isOk(), "AutoBlockElementsJoiner::Run() failed");
-  return result;
+  return ret;
 }
 
 bool HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    PrepareToDeleteNonCollapsedRanges(const HTMLEditor& aHTMLEditor,
-                                      const AutoRangeArray& aRangesToDelete) {
+    PrepareToDeleteNonCollapsedRange(const HTMLEditor& aHTMLEditor,
+                                     const nsRange& aRangeToDelete) {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
 
   mLeftContent = HTMLEditUtils::GetInclusiveAncestorElement(
-      *aRangesToDelete.FirstRangeRef()->GetStartContainer()->AsContent(),
+      *aRangeToDelete.GetStartContainer()->AsContent(),
       HTMLEditUtils::ClosestEditableBlockElement,
       BlockInlineCheck::UseComputedDisplayOutsideStyle);
   mRightContent = HTMLEditUtils::GetInclusiveAncestorElement(
-      *aRangesToDelete.FirstRangeRef()->GetEndContainer()->AsContent(),
+      *aRangeToDelete.GetEndContainer()->AsContent(),
       HTMLEditUtils::ClosestEditableBlockElement,
       BlockInlineCheck::UseComputedDisplayOutsideStyle);
   // Note that mLeftContent and/or mRightContent can be nullptr if editing host
@@ -3381,15 +3507,11 @@ bool HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
   // one or one reaches an inline editing host, we can just delete the content
   // in ranges.
   if (mLeftContent == mRightContent || !mLeftContent || !mRightContent) {
-    MOZ_ASSERT_IF(!mLeftContent || !mRightContent,
-                  aRangesToDelete.FirstRangeRef()
-                          ->GetStartContainer()
-                          ->AsContent()
-                          ->GetEditingHost() == aRangesToDelete.FirstRangeRef()
-                                                    ->GetEndContainer()
-                                                    ->AsContent()
-                                                    ->GetEditingHost());
-    mMode = Mode::DeleteContentInRanges;
+    MOZ_ASSERT_IF(
+        !mLeftContent || !mRightContent,
+        aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost() ==
+            aRangeToDelete.GetEndContainer()->AsContent()->GetEditingHost());
+    mMode = Mode::DeleteContentInRange;
     return true;
   }
 
@@ -3406,100 +3528,79 @@ bool HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
     return true;
   }
 
-  mMode = Mode::DeleteNonCollapsedRanges;
+  mMode = Mode::DeleteNonCollapsedRange;
   return true;
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToDeleteContentInRanges(
+    ComputeRangeToDeleteContentInRange(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete) const {
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRangeToDelete,
+        const Element& aEditingHost) const {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
-  MOZ_ASSERT(mMode == Mode::DeleteContentInRanges);
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->AsContent()
-                 ->GetEditingHost());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->AsContent()
-                 ->GetEditingHost() == aRangesToDelete.FirstRangeRef()
-                                           ->GetEndContainer()
-                                           ->AsContent()
-                                           ->GetEditingHost());
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
+  MOZ_ASSERT(mMode == Mode::DeleteContentInRange);
+  MOZ_ASSERT(aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost());
+  MOZ_ASSERT(
+      aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost() ==
+      aRangeToDelete.GetEndContainer()->AsContent()->GetEditingHost());
   MOZ_ASSERT(!mLeftContent == !mRightContent);
   MOZ_ASSERT_IF(mLeftContent, mLeftContent->IsElement());
-  MOZ_ASSERT_IF(mLeftContent, aRangesToDelete.FirstRangeRef()
-                                  ->GetStartContainer()
-                                  ->IsInclusiveDescendantOf(mLeftContent));
+  MOZ_ASSERT_IF(mLeftContent,
+                aRangeToDelete.GetStartContainer()->IsInclusiveDescendantOf(
+                    mLeftContent));
   MOZ_ASSERT_IF(mRightContent, mRightContent->IsElement());
-  MOZ_ASSERT_IF(mRightContent, aRangesToDelete.FirstRangeRef()
-                                   ->GetEndContainer()
-                                   ->IsInclusiveDescendantOf(mRightContent));
-  MOZ_ASSERT_IF(!mLeftContent,
-                HTMLEditUtils::IsInlineContent(
-                    *aRangesToDelete.FirstRangeRef()
-                         ->GetStartContainer()
-                         ->AsContent()
-                         ->GetEditingHost(),
-                    BlockInlineCheck::UseComputedDisplayOutsideStyle));
+  MOZ_ASSERT_IF(
+      mRightContent,
+      aRangeToDelete.GetEndContainer()->IsInclusiveDescendantOf(mRightContent));
+  MOZ_ASSERT_IF(
+      !mLeftContent,
+      HTMLEditUtils::IsInlineContent(
+          *aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost(),
+          BlockInlineCheck::UseComputedDisplayOutsideStyle));
 
   nsresult rv =
-      mDeleteRangesHandlerConst.ComputeRangesToDeleteRangesWithTransaction(
-          aHTMLEditor, aDirectionAndAmount, aRangesToDelete);
+      mDeleteRangesHandlerConst.ComputeRangeToDeleteRangeWithTransaction(
+          aHTMLEditor, aDirectionAndAmount, aRangeToDelete, aEditingHost);
   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                        "AutoDeleteRangesHandler::"
-                       "ComputeRangesToDeleteRangesWithTransaction() failed");
+                       "ComputeRangeToDeleteRangeWithTransaction() failed");
   return rv;
 }
 
 Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
-    AutoBlockElementsJoiner::DeleteContentInRanges(
+    AutoBlockElementsJoiner::DeleteContentInRange(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-        nsIEditor::EStripWrappers aStripWrappers,
-        AutoRangeArray& aRangesToDelete) {
+        nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete) {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
-  MOZ_ASSERT(mMode == Mode::DeleteContentInRanges);
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
+  MOZ_ASSERT(mMode == Mode::DeleteContentInRange);
   MOZ_ASSERT(mDeleteRangesHandler);
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->AsContent()
-                 ->GetEditingHost());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->AsContent()
-                 ->GetEditingHost() == aRangesToDelete.FirstRangeRef()
-                                           ->GetEndContainer()
-                                           ->AsContent()
-                                           ->GetEditingHost());
+  MOZ_ASSERT(aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost());
+  MOZ_ASSERT(
+      aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost() ==
+      aRangeToDelete.GetEndContainer()->AsContent()->GetEditingHost());
   MOZ_ASSERT_IF(mLeftContent, mLeftContent->IsElement());
-  MOZ_ASSERT_IF(mLeftContent, aRangesToDelete.FirstRangeRef()
-                                  ->GetStartContainer()
-                                  ->IsInclusiveDescendantOf(mLeftContent));
+  MOZ_ASSERT_IF(mLeftContent,
+                aRangeToDelete.GetStartContainer()->IsInclusiveDescendantOf(
+                    mLeftContent));
   MOZ_ASSERT_IF(mRightContent, mRightContent->IsElement());
-  MOZ_ASSERT_IF(mRightContent, aRangesToDelete.FirstRangeRef()
-                                   ->GetEndContainer()
-                                   ->IsInclusiveDescendantOf(mRightContent));
-  MOZ_ASSERT_IF(!mLeftContent,
-                HTMLEditUtils::IsInlineContent(
-                    *aRangesToDelete.FirstRangeRef()
-                         ->GetStartContainer()
-                         ->AsContent()
-                         ->GetEditingHost(),
-                    BlockInlineCheck::UseComputedDisplayOutsideStyle));
-
-  // XXX This is also odd.  We do we simply use
-  //     `DeleteRangesWithTransaction()` only when **first** range is in
-  //     same block?
+  MOZ_ASSERT_IF(
+      mRightContent,
+      aRangeToDelete.GetEndContainer()->IsInclusiveDescendantOf(mRightContent));
+  MOZ_ASSERT_IF(
+      !mLeftContent,
+      HTMLEditUtils::IsInlineContent(
+          *aRangeToDelete.GetStartContainer()->AsContent()->GetEditingHost(),
+          BlockInlineCheck::UseComputedDisplayOutsideStyle));
+
   {
+    AutoRangeArray rangesToDelete(aRangeToDelete);
     AutoTrackDOMRange firstRangeTracker(aHTMLEditor.RangeUpdaterRef(),
-                                        &aRangesToDelete.FirstRangeRef());
+                                        &rangesToDelete.FirstRangeRef());
     Result<CaretPoint, nsresult> caretPointOrError =
-        aHTMLEditor.DeleteRangesWithTransaction(
-            aDirectionAndAmount, aStripWrappers, aRangesToDelete);
+        aHTMLEditor.DeleteRangesWithTransaction(aDirectionAndAmount,
+                                                aStripWrappers, rangesToDelete);
     if (MOZ_UNLIKELY(caretPointOrError.isErr())) {
       if (NS_WARN_IF(caretPointOrError.inspectErr() ==
                      NS_ERROR_EDITOR_DESTROYED)) {
@@ -3522,15 +3623,15 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
     }
   }
 
-  if (NS_WARN_IF(!aRangesToDelete.FirstRangeRef()->IsPositioned())) {
+  if (NS_WARN_IF(!aRangeToDelete.IsPositioned())) {
     return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
   }
 
   nsresult rv =
       mDeleteRangesHandler->DeleteUnnecessaryNodesAndCollapseSelection(
           aHTMLEditor, aDirectionAndAmount,
-          EditorDOMPoint(aRangesToDelete.FirstRangeRef()->StartRef()),
-          EditorDOMPoint(aRangesToDelete.FirstRangeRef()->EndRef()));
+          EditorDOMPoint(aRangeToDelete.StartRef()),
+          EditorDOMPoint(aRangeToDelete.EndRef()));
   if (NS_FAILED(rv)) {
     NS_WARNING(
         "AutoDeleteRangesHandler::DeleteUnnecessaryNodesAndCollapseSelection() "
@@ -3541,63 +3642,59 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToJoinBlockElementsInSameParent(
+    ComputeRangeToJoinBlockElementsInSameParent(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete) const {
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRangeToDelete,
+        const Element& aEditingHost) const {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
   MOZ_ASSERT(mMode == Mode::JoinBlocksInSameParent);
   MOZ_ASSERT(mLeftContent);
   MOZ_ASSERT(mLeftContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->IsInclusiveDescendantOf(mLeftContent));
+  MOZ_ASSERT(aRangeToDelete.GetStartContainer()->IsInclusiveDescendantOf(
+      mLeftContent));
   MOZ_ASSERT(mRightContent);
   MOZ_ASSERT(mRightContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetEndContainer()
-                 ->IsInclusiveDescendantOf(mRightContent));
+  MOZ_ASSERT(
+      aRangeToDelete.GetEndContainer()->IsInclusiveDescendantOf(mRightContent));
   MOZ_ASSERT(mLeftContent->GetParentNode() == mRightContent->GetParentNode());
 
   nsresult rv =
-      mDeleteRangesHandlerConst.ComputeRangesToDeleteRangesWithTransaction(
-          aHTMLEditor, aDirectionAndAmount, aRangesToDelete);
+      mDeleteRangesHandlerConst.ComputeRangeToDeleteRangeWithTransaction(
+          aHTMLEditor, aDirectionAndAmount, aRangeToDelete, aEditingHost);
   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                        "AutoDeleteRangesHandler::"
-                       "ComputeRangesToDeleteRangesWithTransaction() failed");
+                       "ComputeRangeToDeleteRangeWithTransaction() failed");
   return rv;
 }
 
 Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
     AutoBlockElementsJoiner::JoinBlockElementsInSameParent(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-        nsIEditor::EStripWrappers aStripWrappers,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete,
         SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost) {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
   MOZ_ASSERT(mMode == Mode::JoinBlocksInSameParent);
   MOZ_ASSERT(mLeftContent);
   MOZ_ASSERT(mLeftContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->IsInclusiveDescendantOf(mLeftContent));
+  MOZ_ASSERT(aRangeToDelete.GetStartContainer()->IsInclusiveDescendantOf(
+      mLeftContent));
   MOZ_ASSERT(mRightContent);
   MOZ_ASSERT(mRightContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetEndContainer()
-                 ->IsInclusiveDescendantOf(mRightContent));
+  MOZ_ASSERT(
+      aRangeToDelete.GetEndContainer()->IsInclusiveDescendantOf(mRightContent));
   MOZ_ASSERT(mLeftContent->GetParentNode() == mRightContent->GetParentNode());
 
   const bool backspaceInRightBlock =
       aSelectionWasCollapsed == SelectionWasCollapsed::Yes &&
       nsIEditor::DirectionIsBackspace(aDirectionAndAmount);
 
+  AutoRangeArray rangesToDelete(aRangeToDelete);
   Result<CaretPoint, nsresult> caretPointOrError =
       aHTMLEditor.DeleteRangesWithTransaction(aDirectionAndAmount,
-                                              aStripWrappers, aRangesToDelete);
+                                              aStripWrappers, rangesToDelete);
   if (MOZ_UNLIKELY(caretPointOrError.isErr())) {
     NS_WARNING("EditorBase::DeleteRangesWithTransaction() failed");
     return caretPointOrError.propagateErr();
@@ -3686,7 +3783,7 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
 
 Result<bool, nsresult>
 HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToDeleteNodesEntirelyInRangeButKeepTableStructure(
+    ComputeRangeToDeleteNodesEntirelyInRangeButKeepTableStructure(
         const HTMLEditor& aHTMLEditor, nsRange& aRange,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed)
         const {
@@ -3841,39 +3938,34 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    ComputeRangesToDeleteNonCollapsedRanges(
+    ComputeRangeToDeleteNonCollapsedRange(
         const HTMLEditor& aHTMLEditor,
-        nsIEditor::EDirection aDirectionAndAmount,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EDirection aDirectionAndAmount, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost) const {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
   MOZ_ASSERT(mLeftContent);
   MOZ_ASSERT(mLeftContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->IsInclusiveDescendantOf(mLeftContent));
+  MOZ_ASSERT(aRangeToDelete.GetStartContainer()->IsInclusiveDescendantOf(
+      mLeftContent));
   MOZ_ASSERT(mRightContent);
   MOZ_ASSERT(mRightContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetEndContainer()
-                 ->IsInclusiveDescendantOf(mRightContent));
+  MOZ_ASSERT(
+      aRangeToDelete.GetEndContainer()->IsInclusiveDescendantOf(mRightContent));
 
-  for (OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
-    Result<bool, nsresult> result =
-        ComputeRangesToDeleteNodesEntirelyInRangeButKeepTableStructure(
-            aHTMLEditor, range, aSelectionWasCollapsed);
-    if (result.isErr()) {
-      NS_WARNING(
-          "AutoBlockElementsJoiner::"
-          "ComputeRangesToDeleteNodesEntirelyInRangeButKeepTableStructure() "
-          "failed");
-      return result.unwrapErr();
-    }
-    if (!result.unwrap()) {
-      return NS_OK;
-    }
+  Result<bool, nsresult> result =
+      ComputeRangeToDeleteNodesEntirelyInRangeButKeepTableStructure(
+          aHTMLEditor, aRangeToDelete, aSelectionWasCollapsed);
+  if (result.isErr()) {
+    NS_WARNING(
+        "AutoBlockElementsJoiner::"
+        "ComputeRangeToDeleteNodesEntirelyInRangeButKeepTableStructure() "
+        "failed");
+    return result.unwrapErr();
+  }
+  if (!result.unwrap()) {
+    return NS_OK;
   }
 
   AutoInclusiveAncestorBlockElementsJoiner joiner(*mLeftContent,
@@ -3893,68 +3985,62 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
     return NS_OK;
   }
 
-  nsresult rv = joiner.ComputeRangesToDelete(aHTMLEditor, EditorDOMPoint(),
-                                             aRangesToDelete);
+  nsresult rv = joiner.ComputeRangeToDelete(aHTMLEditor, EditorDOMPoint(),
+                                            aRangeToDelete);
   NS_WARNING_ASSERTION(
       NS_SUCCEEDED(rv),
-      "AutoInclusiveAncestorBlockElementsJoiner::ComputeRangesToDelete() "
+      "AutoInclusiveAncestorBlockElementsJoiner::ComputeRangeToDelete() "
       "failed");
   return rv;
 }
 
 Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
-    AutoBlockElementsJoiner::HandleDeleteNonCollapsedRanges(
+    AutoBlockElementsJoiner::HandleDeleteNonCollapsedRange(
         HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-        nsIEditor::EStripWrappers aStripWrappers,
-        AutoRangeArray& aRangesToDelete,
+        nsIEditor::EStripWrappers aStripWrappers, nsRange& aRangeToDelete,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed,
         const Element& aEditingHost) {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.IsCollapsed());
+  MOZ_ASSERT(!aRangeToDelete.Collapsed());
   MOZ_ASSERT(mDeleteRangesHandler);
   MOZ_ASSERT(mLeftContent);
   MOZ_ASSERT(mLeftContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetStartContainer()
-                 ->IsInclusiveDescendantOf(mLeftContent));
+  MOZ_ASSERT(aRangeToDelete.GetStartContainer()->IsInclusiveDescendantOf(
+      mLeftContent));
   MOZ_ASSERT(mRightContent);
   MOZ_ASSERT(mRightContent->IsElement());
-  MOZ_ASSERT(aRangesToDelete.FirstRangeRef()
-                 ->GetEndContainer()
-                 ->IsInclusiveDescendantOf(mRightContent));
+  MOZ_ASSERT(
+      aRangeToDelete.GetEndContainer()->IsInclusiveDescendantOf(mRightContent));
 
   const bool backspaceInRightBlock =
       aSelectionWasCollapsed == SelectionWasCollapsed::Yes &&
       nsIEditor::DirectionIsBackspace(aDirectionAndAmount);
 
-  // Otherwise, delete every nodes in all ranges, then, clean up something.
+  // Otherwise, delete every nodes in the range, then, clean up something.
   EditActionResult result = EditActionResult::IgnoredResult();
   EditorDOMPoint pointToPutCaret;
   while (true) {
+    OwningNonNull<nsRange> rangeToDelete(aRangeToDelete);
     AutoTrackDOMRange firstRangeTracker(aHTMLEditor.RangeUpdaterRef(),
-                                        &aRangesToDelete.FirstRangeRef());
-
-    bool joinInclusiveAncestorBlockElements = true;
-    for (auto& range : aRangesToDelete.Ranges()) {
-      Result<bool, nsresult> deleteResult =
-          DeleteNodesEntirelyInRangeButKeepTableStructure(
-              aHTMLEditor, MOZ_KnownLive(range), aSelectionWasCollapsed);
-      if (MOZ_UNLIKELY(deleteResult.isErr())) {
-        NS_WARNING(
-            "AutoBlockElementsJoiner::"
-            "DeleteNodesEntirelyInRangeButKeepTableStructure() failed");
-        return deleteResult.propagateErr();
-      }
-      // XXX Completely odd.  Why don't we join blocks around each range?
-      joinInclusiveAncestorBlockElements &= deleteResult.unwrap();
+                                        &rangeToDelete);
+
+    Result<bool, nsresult> deleteResult =
+        DeleteNodesEntirelyInRangeButKeepTableStructure(
+            aHTMLEditor, rangeToDelete, aSelectionWasCollapsed);
+    if (MOZ_UNLIKELY(deleteResult.isErr())) {
+      NS_WARNING(
+          "AutoBlockElementsJoiner::"
+          "DeleteNodesEntirelyInRangeButKeepTableStructure() failed");
+      return deleteResult.propagateErr();
     }
 
+    const bool joinInclusiveAncestorBlockElements = deleteResult.unwrap();
+
     // Check endpoints for possible text deletion.  We can assume that if
-    // text node is found, we can delete to end or to begining as
+    // text node is found, we can delete to end or to beginning as
     // appropriate, since the case where both sel endpoints in same text
     // node was already handled (we wouldn't be here)
-    nsresult rv = DeleteTextAtStartAndEndOfRange(
-        aHTMLEditor, MOZ_KnownLive(aRangesToDelete.FirstRangeRef()));
+    nsresult rv = DeleteTextAtStartAndEndOfRange(aHTMLEditor, rangeToDelete);
     if (NS_FAILED(rv)) {
       NS_WARNING(
           "AutoBlockElementsJoiner::DeleteTextAtStartAndEndOfRange() failed");
@@ -3978,7 +4064,7 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
     // be collapsed to the end of the selection, if deleting backward the
     // selection should be collapsed to the beginning of the selection.
     // But if we're not joining then the selection should collapse to the
-    // beginning of the selection if we'redeleting forward, because the
+    // beginning of the selection if we're deleting forward, because the
     // end of the selection will still be in the next block. And same
     // thing for deleting backwards (selection should collapse to the end,
     // because the beginning will still be in the first block). See Bug
@@ -4024,7 +4110,7 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
   // AutoInclusiveAncestorBlockElementsJoiner computed new caret position, we
   // should use it.  Otherwise, we should keep the traditional behavior.
   if (result.Handled() && pointToPutCaret.IsSet()) {
-    EditorDOMRange range(aRangesToDelete.FirstRangeRef());
+    EditorDOMRange range(aRangeToDelete);
     nsresult rv =
         mDeleteRangesHandler->DeleteUnnecessaryNodes(aHTMLEditor, range);
     if (NS_FAILED(rv)) {
@@ -4054,8 +4140,8 @@ Result<EditActionResult, nsresult> HTMLEditor::AutoDeleteRangesHandler::
   nsresult rv =
       mDeleteRangesHandler->DeleteUnnecessaryNodesAndCollapseSelection(
           aHTMLEditor, aDirectionAndAmount,
-          EditorDOMPoint(aRangesToDelete.FirstRangeRef()->StartRef()),
-          EditorDOMPoint(aRangesToDelete.FirstRangeRef()->EndRef()));
+          EditorDOMPoint(aRangeToDelete.StartRef()),
+          EditorDOMPoint(aRangeToDelete.EndRef()));
   if (NS_FAILED(rv)) {
     NS_WARNING(
         "AutoDeleteRangesHandler::DeleteUnnecessaryNodesAndCollapseSelection() "
@@ -4316,21 +4402,26 @@ HTMLEditor::AutoDeleteRangesHandler::DeleteParentBlocksWithTransactionIfEmpty(
 }
 
 nsresult
-HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDeleteRangesWithTransaction(
+HTMLEditor::AutoDeleteRangesHandler::ComputeRangeToDeleteRangeWithTransaction(
     const HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
-    AutoRangeArray& aRangesToDelete) const {
+    nsRange& aRangeToDelete, const Element& aEditingHost) const {
   MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
-  MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
 
-  EditorBase::HowToHandleCollapsedRange howToHandleCollapsedRange =
+  const EditorBase::HowToHandleCollapsedRange howToHandleCollapsedRange =
       EditorBase::HowToHandleCollapsedRangeFor(aDirectionAndAmount);
-  if (NS_WARN_IF(aRangesToDelete.IsCollapsed() &&
-                 howToHandleCollapsedRange ==
-                     EditorBase::HowToHandleCollapsedRange::Ignore)) {
-    return NS_ERROR_FAILURE;
+  if (MOZ_UNLIKELY(aRangeToDelete.Collapsed() &&
+                   howToHandleCollapsedRange ==
+                       EditorBase::HowToHandleCollapsedRange::Ignore)) {
+    return NS_SUCCESS_DOM_NO_OPERATION;
   }
 
-  auto extendRangeToSelectCharacterForward =
+  // If it's not collapsed, `DeleteRangeTransaction::Create()` will be called
+  // with it and `DeleteRangeTransaction` won't modify the range.
+  if (!aRangeToDelete.Collapsed()) {
+    return NS_OK;
+  }
+
+  const auto ExtendRangeToSelectCharacterForward =
       [](nsRange& aRange, const EditorRawDOMPointInText& aCaretPoint) -> void {
     const nsTextFragment& textFragment =
         aCaretPoint.ContainerAs<Text>()->TextFragment();
@@ -4352,7 +4443,7 @@ HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDeleteRangesWithTransaction(
     NS_WARNING_ASSERTION(NS_SUCCEEDED(rvIgnored),
                          "nsRange::SetStartAndEnd() failed");
   };
-  auto extendRangeToSelectCharacterBackward =
+  const auto ExtendRangeToSelectCharacterBackward =
       [](nsRange& aRange, const EditorRawDOMPointInText& aCaretPoint) -> void {
     if (aCaretPoint.IsStartOfContainer()) {
       return;
@@ -4378,127 +4469,116 @@ HTMLEditor::AutoDeleteRangesHandler::ComputeRangesToDeleteRangesWithTransaction(
                          "nsRange::SetStartAndEnd() failed");
   };
 
-  RefPtr<Element> editingHost = aHTMLEditor.ComputeEditingHost();
-  for (OwningNonNull<nsRange>& range : aRangesToDelete.Ranges()) {
-    // If it's not collapsed, `DeleteRangeTransaction::Create()` will be called
-    // with it and `DeleteRangeTransaction` won't modify the range.
-    if (!range->Collapsed()) {
-      continue;
+  // In the other cases, `EditorBase::CreateTransactionForCollapsedRange()`
+  // will handle the collapsed range.
+  EditorRawDOMPoint caretPoint(aRangeToDelete.StartRef());
+  if (howToHandleCollapsedRange ==
+          EditorBase::HowToHandleCollapsedRange::ExtendBackward &&
+      caretPoint.IsStartOfContainer()) {
+    nsIContent* previousEditableContent = HTMLEditUtils::GetPreviousContent(
+        *caretPoint.GetContainer(), {WalkTreeOption::IgnoreNonEditableNode},
+        BlockInlineCheck::Unused, &aEditingHost);
+    if (!previousEditableContent) {
+      return NS_OK;
     }
-
-    if (howToHandleCollapsedRange ==
-        EditorBase::HowToHandleCollapsedRange::Ignore) {
-      continue;
+    if (!previousEditableContent->IsText()) {
+      IgnoredErrorResult ignoredError;
+      aRangeToDelete.SelectNode(*previousEditableContent, ignoredError);
+      NS_WARNING_ASSERTION(!ignoredError.Failed(),
+                           "nsRange::SelectNode() failed");
+      return NS_OK;
     }
 
-    // In the other cases, `EditorBase::CreateTransactionForCollapsedRange()`
-    // will handle the collapsed range.
-    EditorRawDOMPoint caretPoint(range->StartRef());
-    if (howToHandleCollapsedRange ==
-            EditorBase::HowToHandleCollapsedRange::ExtendBackward &&
-        caretPoint.IsStartOfContainer()) {
-      nsIContent* previousEditableContent = HTMLEditUtils::GetPreviousContent(
-          *caretPoint.GetContainer(), {WalkTreeOption::IgnoreNonEditableNode},
-          BlockInlineCheck::Unused, editingHost);
-      if (!previousEditableContent) {
-        continue;
-      }
-      if (!previousEditableContent->IsText()) {
-        IgnoredErrorResult ignoredError;
-        range->SelectNode(*previousEditableContent, ignoredError);
-        NS_WARNING_ASSERTION(!ignoredError.Failed(),
-                             "nsRange::SelectNode() failed");
-        continue;
-      }
+    ExtendRangeToSelectCharacterBackward(
+        aRangeToDelete,
+        EditorRawDOMPointInText::AtEndOf(*previousEditableContent->AsText()));
+    return NS_OK;
+  }
 
-      extendRangeToSelectCharacterBackward(
-          range,
-          EditorRawDOMPointInText::AtEndOf(*previousEditableContent->AsText()));
-      continue;
+  if (howToHandleCollapsedRange ==
+          EditorBase::HowToHandleCollapsedRange::ExtendForward &&
+      caretPoint.IsEndOfContainer()) {
+    nsIContent* nextEditableContent = HTMLEditUtils::GetNextContent(
+        *caretPoint.GetContainer(), {WalkTreeOption::IgnoreNonEditableNode},
+        BlockInlineCheck::Unused, &aEditingHost);
+    if (!nextEditableContent) {
+      return NS_OK;
     }
 
-    if (howToHandleCollapsedRange ==
-            EditorBase::HowToHandleCollapsedRange::ExtendForward &&
-        caretPoint.IsEndOfContainer()) {
-      nsIContent* nextEditableContent = HTMLEditUtils::GetNextContent(
-          *caretPoint.GetContainer(), {WalkTreeOption::IgnoreNonEditableNode},
-          BlockInlineCheck::Unused, editingHost);
-      if (!nextEditableContent) {
-        continue;
-      }
-
-      if (!nextEditableContent->IsText()) {
-        IgnoredErrorResult ignoredError;
-        range->SelectNode(*nextEditableContent, ignoredError);
-        NS_WARNING_ASSERTION(!ignoredError.Failed(),
-                             "nsRange::SelectNode() failed");
-        continue;
-      }
-
-      extendRangeToSelectCharacterForward(
-          range, EditorRawDOMPointInText(nextEditableContent->AsText(), 0));
-      continue;
+    if (!nextEditableContent->IsText()) {
+      IgnoredErrorResult ignoredError;
+      aRangeToDelete.SelectNode(*nextEditableContent, ignoredError);
+      NS_WARNING_ASSERTION(!ignoredError.Failed(),
+                           "nsRange::SelectNode() failed");
+      return NS_OK;
     }
 
-    if (caretPoint.IsInTextNode()) {
-      if (howToHandleCollapsedRange ==
-          EditorBase::HowToHandleCollapsedRange::ExtendBackward) {
-        extendRangeToSelectCharacterBackward(
-            range, EditorRawDOMPointInText(caretPoint.ContainerAs<Text>(),
-                                           caretPoint.Offset()));
-        continue;
-      }
-      extendRangeToSelectCharacterForward(
-          range, EditorRawDOMPointInText(caretPoint.ContainerAs<Text>(),
-                                         caretPoint.Offset()));
-      continue;
+    ExtendRangeToSelectCharacterForward(
+        aRangeToDelete,
+        EditorRawDOMPointInText(nextEditableContent->AsText(), 0));
+    return NS_OK;
+  }
+
+  if (caretPoint.IsInTextNode()) {
+    if (howToHandleCollapsedRange ==
+        EditorBase::HowToHandleCollapsedRange::ExtendBackward) {
+      ExtendRangeToSelectCharacterBackward(
+          aRangeToDelete,
+          EditorRawDOMPointInText(caretPoint.ContainerAs<Text>(),
+                                  caretPoint.Offset()));
+      return NS_OK;
     }
+    ExtendRangeToSelectCharacterForward(
+        aRangeToDelete, EditorRawDOMPointInText(caretPoint.ContainerAs<Text>(),
+                                                caretPoint.Offset()));
+    return NS_OK;
+  }
 
-    nsIContent* editableContent =
+  nsIContent* editableContent =
+      howToHandleCollapsedRange ==
+              EditorBase::HowToHandleCollapsedRange::ExtendBackward
+          ? HTMLEditUtils::GetPreviousContent(
+                caretPoint, {WalkTreeOption::IgnoreNonEditableNode},
+                BlockInlineCheck::Unused, &aEditingHost)
+          : HTMLEditUtils::GetNextContent(
+                caretPoint, {WalkTreeOption::IgnoreNonEditableNode},
+                BlockInlineCheck::Unused, &aEditingHost);
+  if (!editableContent) {
+    return NS_OK;
+  }
+  while (editableContent && editableContent->IsCharacterData() &&
+         !editableContent->Length()) {
+    editableContent =
         howToHandleCollapsedRange ==
                 EditorBase::HowToHandleCollapsedRange::ExtendBackward
             ? HTMLEditUtils::GetPreviousContent(
-                  caretPoint, {WalkTreeOption::IgnoreNonEditableNode},
-                  BlockInlineCheck::Unused, editingHost)
+                  *editableContent, {WalkTreeOption::IgnoreNonEditableNode},
+                  BlockInlineCheck::Unused, &aEditingHost)
             : HTMLEditUtils::GetNextContent(
-                  caretPoint, {WalkTreeOption::IgnoreNonEditableNode},
-                  BlockInlineCheck::Unused, editingHost);
-    if (!editableContent) {
-      continue;
-    }
-    while (editableContent && editableContent->IsCharacterData() &&
-           !editableContent->Length()) {
-      editableContent =
-          howToHandleCollapsedRange ==
-                  EditorBase::HowToHandleCollapsedRange::ExtendBackward
-              ? HTMLEditUtils::GetPreviousContent(
-                    *editableContent, {WalkTreeOption::IgnoreNonEditableNode},
-                    BlockInlineCheck::Unused, editingHost)
-              : HTMLEditUtils::GetNextContent(
-                    *editableContent, {WalkTreeOption::IgnoreNonEditableNode},
-                    BlockInlineCheck::Unused, editingHost);
-    }
-    if (!editableContent) {
-      continue;
-    }
+                  *editableContent, {WalkTreeOption::IgnoreNonEditableNode},
+                  BlockInlineCheck::Unused, &aEditingHost);
+  }
+  if (!editableContent) {
+    return NS_OK;
+  }
 
-    if (!editableContent->IsText()) {
-      IgnoredErrorResult ignoredError;
-      range->SelectNode(*editableContent, ignoredError);
-      NS_WARNING_ASSERTION(!ignoredError.Failed(),
-                           "nsRange::SelectNode() failed");
-      continue;
-    }
+  if (!editableContent->IsText()) {
+    IgnoredErrorResult ignoredError;
+    aRangeToDelete.SelectNode(*editableContent, ignoredError);
+    NS_WARNING_ASSERTION(!ignoredError.Failed(),
+                         "nsRange::SelectNode() failed, but ignored");
+    return NS_OK;
+  }
 
-    if (howToHandleCollapsedRange ==
-        EditorBase::HowToHandleCollapsedRange::ExtendBackward) {
-      extendRangeToSelectCharacterBackward(
-          range, EditorRawDOMPointInText::AtEndOf(*editableContent->AsText()));
-      continue;
-    }
-    extendRangeToSelectCharacterForward(
-        range, EditorRawDOMPointInText(editableContent->AsText(), 0));
+  if (howToHandleCollapsedRange ==
+      EditorBase::HowToHandleCollapsedRange::ExtendBackward) {
+    ExtendRangeToSelectCharacterBackward(
+        aRangeToDelete,
+        EditorRawDOMPointInText::AtEndOf(*editableContent->AsText()));
+    return NS_OK;
   }
+  ExtendRangeToSelectCharacterForward(
+      aRangeToDelete, EditorRawDOMPointInText(editableContent->AsText(), 0));
 
   return NS_OK;
 }
@@ -4893,10 +4973,9 @@ Result<bool, nsresult> HTMLEditor::AutoDeleteRangesHandler::
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
-    AutoInclusiveAncestorBlockElementsJoiner::ComputeRangesToDelete(
+    AutoInclusiveAncestorBlockElementsJoiner::ComputeRangeToDelete(
         const HTMLEditor& aHTMLEditor, const EditorDOMPoint& aCaretPoint,
-        AutoRangeArray& aRangesToDelete) const {
-  MOZ_ASSERT(!aRangesToDelete.Ranges().IsEmpty());
+        nsRange& aRangeToDelete) const {
   MOZ_ASSERT(mLeftBlockElement);
   MOZ_ASSERT(mRightBlockElement);
 
@@ -4904,8 +4983,8 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
     if (!aCaretPoint.IsSet()) {
       return NS_OK;  // The ranges are not collapsed, keep them as-is.
     }
-    nsresult rv = aRangesToDelete.Collapse(aCaretPoint);
-    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "AutoRangeArray::Collapse() failed");
+    nsresult rv = aRangeToDelete.CollapseTo(aCaretPoint.ToRawRangeBoundary());
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "nsRange::CollapseTo() failed");
     return rv;
   }
 
@@ -4927,8 +5006,7 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
   if (!aCaretPoint.IsSet()) {
     // Don't shrink the original range.
     bool noNeedToChangeStart = false;
-    const auto atStart =
-        aRangesToDelete.GetFirstRangeStartPoint<EditorDOMPoint>();
+    const EditorDOMPoint atStart(aRangeToDelete.StartRef());
     if (atStart.IsBefore(range.StartRef())) {
       // If the range starts from end of a container, and computed block
       // boundaries range starts from an invisible `<br>` element,  we
@@ -4948,22 +5026,19 @@ nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
               : nullptr;
       if (!nextContent || nextContent != range.StartRef().GetChild()) {
         noNeedToChangeStart = true;
-        range.SetStart(
-            aRangesToDelete.GetFirstRangeStartPoint<EditorDOMPoint>());
+        range.SetStart(EditorRawDOMPoint(aRangeToDelete.StartRef()));
       }
     }
-    if (range.EndRef().IsBefore(
-            aRangesToDelete.GetFirstRangeEndPoint<EditorRawDOMPoint>())) {
+    if (range.EndRef().IsBefore(EditorRawDOMPoint(aRangeToDelete.EndRef()))) {
       if (noNeedToChangeStart) {
         return NS_OK;  // We don't need to modify the range.
       }
-      range.SetEnd(aRangesToDelete.GetFirstRangeEndPoint<EditorDOMPoint>());
+      range.SetEnd(EditorRawDOMPoint(aRangeToDelete.EndRef()));
     }
   }
-  // XXX Oddly, we join blocks only at the first range.
-  nsresult rv = aRangesToDelete.FirstRangeRef()->SetStartAndEnd(
-      range.StartRef().ToRawRangeBoundary(),
-      range.EndRef().ToRawRangeBoundary());
+  nsresult rv =
+      aRangeToDelete.SetStartAndEnd(range.StartRef().ToRawRangeBoundary(),
+                                    range.EndRef().ToRawRangeBoundary());
   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                        "AutoRangeArray::SetStartAndEnd() failed");
   return rv;
@@ -6666,23 +6741,31 @@ HTMLEditor::AutoDeleteRangesHandler::ExtendOrShrinkRangeToDelete(
     return Err(NS_ERROR_FAILURE);
   }
 
-  // Look for the common ancestor's block element.  It's fine that we get
-  // non-editable block element which is ancestor of inline editing host
-  // because the following code checks editing host too.
-  const Element* const maybeNonEditableBlockElement =
-      HTMLEditUtils::GetInclusiveAncestorElement(
-          *commonAncestor, HTMLEditUtils::ClosestBlockElement,
-          BlockInlineCheck::UseComputedDisplayOutsideStyle);
-  if (NS_WARN_IF(!maybeNonEditableBlockElement)) {
+  // Editing host may be nested and outer one could have focus.  Let's use
+  // the closest editing host instead.
+  const RefPtr<Element> closestEditingHost =
+      aHTMLEditor.ComputeEditingHost(*commonAncestor, LimitInBodyElement::No);
+  if (NS_WARN_IF(!closestEditingHost)) {
     return Err(NS_ERROR_FAILURE);
   }
 
-  // Set up for loops and cache our root element
-  RefPtr<Element> editingHost = aHTMLEditor.ComputeEditingHost();
-  if (NS_WARN_IF(!editingHost)) {
-    return Err(NS_ERROR_FAILURE);
-  }
+  // Look for the common ancestor's block element in the editing host.  It's
+  // fine that we get non-editable block element which is ancestor of inline
+  // editing host because the following code checks editing host too.
+  const RefPtr<Element> closestBlockAncestorOrInlineEditingHost = [&]() {
+    // Note that if non-closest editing host has focus, found block may be
+    // non-editable.
+    if (Element* const maybeEditableBlockElement =
+            HTMLEditUtils::GetInclusiveAncestorElement(
+                *commonAncestor, HTMLEditUtils::ClosestBlockElement,
+                BlockInlineCheck::UseComputedDisplayOutsideStyle,
+                closestEditingHost)) {
+      return maybeEditableBlockElement;
+    }
+    return closestEditingHost.get();
+  }();
 
+  // Set up for loops and cache our root element
   // If only one list element is selected, and if the list element is empty,
   // we should delete only the list element.  Or if the list element is not
   // empty, we should make the list has only one empty list item element.
@@ -6712,18 +6795,18 @@ HTMLEditor::AutoDeleteRangesHandler::ExtendOrShrinkRangeToDelete(
 
   // Find previous visible things before start of selection
   EditorRawDOMRange rangeToDelete(aRangeToDelete);
-  if (rangeToDelete.StartRef().GetContainer() != maybeNonEditableBlockElement &&
-      rangeToDelete.StartRef().GetContainer() != editingHost) {
+  if (rangeToDelete.StartRef().GetContainer() !=
+      closestBlockAncestorOrInlineEditingHost) {
     for (;;) {
       WSScanResult backwardScanFromStartResult =
           WSRunScanner::ScanPreviousVisibleNodeOrBlockBoundary(
-              editingHost, rangeToDelete.StartRef(),
+              closestEditingHost, rangeToDelete.StartRef(),
               BlockInlineCheck::UseComputedDisplayOutsideStyle);
       if (!backwardScanFromStartResult.ReachedCurrentBlockBoundary()) {
         break;
       }
       MOZ_ASSERT(backwardScanFromStartResult.GetContent() ==
-                 WSRunScanner(editingHost, rangeToDelete.StartRef(),
+                 WSRunScanner(closestEditingHost, rangeToDelete.StartRef(),
                               BlockInlineCheck::UseComputedDisplayOutsideStyle)
                      .GetStartReasonContent());
       // We want to keep looking up.  But stop if we are crossing table
@@ -6731,8 +6814,8 @@ HTMLEditor::AutoDeleteRangesHandler::ExtendOrShrinkRangeToDelete(
       if (HTMLEditUtils::IsAnyTableElement(
               backwardScanFromStartResult.GetContent()) ||
           backwardScanFromStartResult.GetContent() ==
-              maybeNonEditableBlockElement ||
-          backwardScanFromStartResult.GetContent() == editingHost) {
+              closestBlockAncestorOrInlineEditingHost ||
+          backwardScanFromStartResult.GetContent() == closestEditingHost) {
         break;
       }
       // Don't cross list element boundary because we don't want to delete list
@@ -6767,11 +6850,11 @@ HTMLEditor::AutoDeleteRangesHandler::ExtendOrShrinkRangeToDelete(
 
   // Find next visible things after end of selection
   EditorDOMPoint atFirstInvisibleBRElement;
-  if (rangeToDelete.EndRef().GetContainer() != maybeNonEditableBlockElement &&
-      rangeToDelete.EndRef().GetContainer() != editingHost) {
+  if (rangeToDelete.EndRef().GetContainer() !=
+      closestBlockAncestorOrInlineEditingHost) {
     for (;;) {
       WSRunScanner wsScannerAtEnd(
-          editingHost, rangeToDelete.EndRef(),
+          closestEditingHost, rangeToDelete.EndRef(),
           BlockInlineCheck::UseComputedDisplayOutsideStyle);
       WSScanResult forwardScanFromEndResult =
           wsScannerAtEnd.ScanNextVisibleNodeOrBlockBoundaryFrom(
@@ -6806,8 +6889,7 @@ HTMLEditor::AutoDeleteRangesHandler::ExtendOrShrinkRangeToDelete(
         if (HTMLEditUtils::IsAnyTableElement(
                 forwardScanFromEndResult.GetContent()) ||
             forwardScanFromEndResult.GetContent() ==
-                maybeNonEditableBlockElement ||
-            forwardScanFromEndResult.GetContent() == editingHost) {
+                closestBlockAncestorOrInlineEditingHost) {
           break;
         }
         // Don't cross flex-item/grid-item boundary to make new content inserted
diff --git a/editor/libeditor/TextEditor.cpp b/editor/libeditor/TextEditor.cpp
index 2403dd1f55..9f6fb86eb3 100644
--- a/editor/libeditor/TextEditor.cpp
+++ b/editor/libeditor/TextEditor.cpp
@@ -40,7 +40,6 @@
 #include "nsCaret.h"
 #include "nsCharTraits.h"
 #include "nsComponentManagerUtils.h"
-#include "nsContentCID.h"
 #include "nsContentList.h"
 #include "nsDebug.h"
 #include "nsDependentSubstring.h"
diff --git a/editor/libeditor/tests/browserscope/test_richtext.html b/editor/libeditor/tests/browserscope/test_richtext.html
index c07f0a366a..3322522929 100644
--- a/editor/libeditor/tests/browserscope/test_richtext.html
+++ b/editor/libeditor/tests/browserscope/test_richtext.html
@@ -23,7 +23,7 @@ SimpleTest.waitForExplicitFinish();
 // Running all of the tests can take a long time, try to account for it
 SimpleTest.requestLongerTimeout(5);
 
-function sendScore(results, continueParams) {
+function sendScore(results) {
   ok(results.length > 1, "At least one test should have been run");
   for (var i = 1; i < results.length; ++i) {
     var result = results[i];
diff --git a/editor/libeditor/tests/mochitest.toml b/editor/libeditor/tests/mochitest.toml
index 5af13503f7..15a6d4c379 100644
--- a/editor/libeditor/tests/mochitest.toml
+++ b/editor/libeditor/tests/mochitest.toml
@@ -418,6 +418,8 @@ skip-if = ["os == 'android'"] #Bug 1575739
 
 ["test_cmd_paragraphState.html"]
 
+["test_command_state_when_readonly.html"]
+
 ["test_composition_event_created_in_chrome.html"]
 
 ["test_composition_with_highlight_in_texteditor.html"]
diff --git a/editor/libeditor/tests/test_bug1053048.html b/editor/libeditor/tests/test_bug1053048.html
index 4f9df5e602..416d6442d6 100644
--- a/editor/libeditor/tests/test_bug1053048.html
+++ b/editor/libeditor/tests/test_bug1053048.html
@@ -37,7 +37,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1053048
     // synthesizing the key press.  So, we don't need to check whether a
     // notification actually comes here.
     let selectionListener = {
-      notifySelectionChanged(aDocument, aSelection, aReason, aAmount) {
+      notifySelectionChanged() {
         ok(true, "selectionStart: " + textarea.selectionStart);
         ok(true, "selectionEnd: " + textarea.selectionEnd);
       },
diff --git a/editor/libeditor/tests/test_bug1649005.html b/editor/libeditor/tests/test_bug1649005.html
index fbd8e16ef8..5e08e16493 100644
--- a/editor/libeditor/tests/test_bug1649005.html
+++ b/editor/libeditor/tests/test_bug1649005.html
@@ -11,7 +11,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1649005
   <script src="/tests/SimpleTest/EventUtils.js"></script>
   <script>
   /** Test for bug 1649005, bug 1779343 **/
-  window.addEventListener("DOMContentLoaded", (event) => {
+  window.addEventListener("DOMContentLoaded", () => {
     SimpleTest.waitForExplicitFinish();
     SimpleTest.waitForFocus(function() {
       document.body.textContent = ""; // It would be \n\n otherwise...
diff --git a/editor/libeditor/tests/test_bug1659276.html b/editor/libeditor/tests/test_bug1659276.html
index 6789db2e77..6286e58327 100644
--- a/editor/libeditor/tests/test_bug1659276.html
+++ b/editor/libeditor/tests/test_bug1659276.html
@@ -63,7 +63,7 @@ SimpleTest.waitForExplicitFinish();
 SimpleTest.waitForFocus(async () => {

   function waitForTickOfRefeshDriver() {

     function awaitOneRefresh() {

-      return new Promise(function(aResolve, aReject) {

+      return new Promise(function(aResolve) {

         requestAnimationFrame(aResolve);

       });

     }

diff --git a/editor/libeditor/tests/test_bug502673.html b/editor/libeditor/tests/test_bug502673.html
index 0850cf3de0..fcfb1f329e 100644
--- a/editor/libeditor/tests/test_bug502673.html
+++ b/editor/libeditor/tests/test_bug502673.html
@@ -37,7 +37,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=502673
           editor.removeDocumentStateListener(this);
         },
 
-        NotifyDocumentStateChanged(aNowDirty) {
+        NotifyDocumentStateChanged() {
           var editor = SpecialPowers.wrap(this.input).editor;
           editor.removeDocumentStateListener(this);
         },
diff --git a/editor/libeditor/tests/test_bug525389.html b/editor/libeditor/tests/test_bug525389.html
index 500720d92a..25c6e2b8e3 100644
--- a/editor/libeditor/tests/test_bug525389.html
+++ b/editor/libeditor/tests/test_bug525389.html
@@ -17,7 +17,7 @@ function getLoadContext() {
 
 async function runTest() {
   var pasteCount = 0;
-  var pasteFunc = function(event) { pasteCount++; };
+  var pasteFunc = function() { pasteCount++; };
 
   function verifyContent(s) {
     var e = document.getElementById("i1");
diff --git a/editor/libeditor/tests/test_bug569988.html b/editor/libeditor/tests/test_bug569988.html
index c4d4b040ba..6181668374 100644
--- a/editor/libeditor/tests/test_bug569988.html
+++ b/editor/libeditor/tests/test_bug569988.html
@@ -33,7 +33,7 @@ function runTest() {
     os.addObserver(onPromptLoad, "common-dialog-loaded");
     os.addObserver(onPromptLoad, "tabmodal-dialog-loaded");
 
-    function onPromptLoad(subject, topic, data) {
+    function onPromptLoad(subject) {
       let ui = subject.Dialog ? subject.Dialog.ui : undefined;
       if (!ui) {
         // subject is an tab prompt, find the elements ourselves
@@ -54,19 +54,15 @@ function runTest() {
       sendAsyncMessage("ok", [true, "onPromptFocus is called"]);
       gPromptInput.removeEventListener("focus", onPromptFocus);
 
-      var listenerService = Services.els;
-
       var listener = {
         handleEvent: function _hv(aEvent) {
           var isPrevented = aEvent.defaultPrevented;
           sendAsyncMessage("ok", [!isPrevented,
                            "ESC key event is prevented by editor"]);
-          listenerService.removeSystemEventListener(gPromptInput, "keypress",
-                                                    listener, false);
+          gPromptInput.removeEventListener("keypress", listener, { mozSystemGroup: true });
         },
       };
-      listenerService.addSystemEventListener(gPromptInput, "keypress",
-                                             listener, false);
+      gPromptInput.addEventListener("keypress", listener, { mozSystemGroup: true });
 
       sendAsyncMessage("info", "sending key");
       var EventUtils = {};
diff --git a/editor/libeditor/tests/test_bug607584.xhtml b/editor/libeditor/tests/test_bug607584.xhtml
index f610de544b..37bb3dc5a4 100644
--- a/editor/libeditor/tests/test_bug607584.xhtml
+++ b/editor/libeditor/tests/test_bug607584.xhtml
@@ -44,7 +44,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=607584
     QueryInterface: ChromeUtils.generateQI(["nsIWebProgressListener",
                                             "nsISupportsWeakReference"]),
 
-    onStateChange(aWebProgress, aRequest, aStateFlags, aStatus)
+    onStateChange(aWebProgress, aRequest, aStateFlags)
     {
         if (aStateFlags & Ci.nsIWebProgressListener.STATE_STOP)
         {
@@ -71,25 +71,23 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=607584
     },
 
 
-    onProgressChange(aWebProgress, aRequest,
-                                aCurSelfProgress, aMaxSelfProgress,
-                                aCurTotalProgress, aMaxTotalProgress)
+    onProgressChange()
       {
       },
 
-    onLocationChange(aWebProgress, aRequest, aLocation, aFlags)
+    onLocationChange()
       {
       },
 
-    onStatusChange(aWebProgress, aRequest, aStatus, aMessage)
+    onStatusChange()
       {
       },
 
-    onSecurityChange(aWebProgress, aRequest, aState)
+    onSecurityChange()
       {
       },
 
-    onContentBlockingEvent(aWebProgress, aRequest, aEvent)
+    onContentBlockingEvent()
       {
       },
 
diff --git a/editor/libeditor/tests/test_bug611182.html b/editor/libeditor/tests/test_bug611182.html
index 7843156fda..125dcacb62 100644
--- a/editor/libeditor/tests/test_bug611182.html
+++ b/editor/libeditor/tests/test_bug611182.html
@@ -92,7 +92,7 @@ SimpleTest.waitForFocus(function() {
   // start running all tests.
   var myXHR = new XMLHttpRequest();
   myXHR.open("GET", "file_bug611182.sjs?queryTotalTests");
-  myXHR.onload = function(e) {
+  myXHR.onload = function() {
     totalTests = myXHR.responseText;
     runAllTests();
   };
diff --git a/editor/libeditor/tests/test_bug616590.xhtml b/editor/libeditor/tests/test_bug616590.xhtml
index 1f6cb3d0f8..4a4bad7224 100644
--- a/editor/libeditor/tests/test_bug616590.xhtml
+++ b/editor/libeditor/tests/test_bug616590.xhtml
@@ -43,7 +43,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=616590
     QueryInterface: ChromeUtils.generateQI(["nsIWebProgressListener",
                                             "nsISupportsWeakReference"]),
 
-    onStateChange(aWebProgress, aRequest, aStateFlags, aStatus)
+    onStateChange(aWebProgress, aRequest, aStateFlags)
     {
       if (aStateFlags & Ci.nsIWebProgressListener.STATE_STOP)
       {
@@ -60,25 +60,23 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=616590
     },
 
 
-    onProgressChange(aWebProgress, aRequest,
-                                aCurSelfProgress, aMaxSelfProgress,
-                                aCurTotalProgress, aMaxTotalProgress)
+    onProgressChange()
     {
     },
 
-    onLocationChange(aWebProgress, aRequest, aLocation, aFlags)
+    onLocationChange()
     {
     },
 
-    onStatusChange(aWebProgress, aRequest, aStatus, aMessage)
+    onStatusChange()
     {
     },
 
-    onSecurityChange(aWebProgress, aRequest, aState)
+    onSecurityChange()
     {
     },
 
-    onContentBlockingEvent(aWebProgress, aRequest, aEvent)
+    onContentBlockingEvent()
     {
     },
 
diff --git a/editor/libeditor/tests/test_bug674770-1.html b/editor/libeditor/tests/test_bug674770-1.html
index 0b6089e0ef..d8e792ccd2 100644
--- a/editor/libeditor/tests/test_bug674770-1.html
+++ b/editor/libeditor/tests/test_bug674770-1.html
@@ -55,7 +55,7 @@ function startTests() {
     SimpleTest.executeSoon(runNextTest);
   }, false);
 
-  SpecialPowers.addSystemEventListener(window, "auxclick", function(aEvent) {
+  SpecialPowers.wrap(window).addEventListener("auxclick", function(aEvent) {
     // When the click event should cause default action, e.g., opening the link,
     // the event shouldn't have been consumed except the link handler.
     // However, in e10s mode, it's not consumed during propagating the event but
@@ -74,7 +74,7 @@ function startTests() {
       // In this case, "storage" event won't be fired.
       SimpleTest.executeSoon(runNextTest);
     }
-  }, false);
+  }, { mozSystemGroup: true });
 
   SimpleTest.executeSoon(runNextTest);
 }
diff --git a/editor/libeditor/tests/test_bug674770-2.html b/editor/libeditor/tests/test_bug674770-2.html
index 9b05277052..ab2fbca68b 100644
--- a/editor/libeditor/tests/test_bug674770-2.html
+++ b/editor/libeditor/tests/test_bug674770-2.html
@@ -320,7 +320,7 @@ function initForBodyEditableDocumentTests() {
   frameDocument.getElementById("editor2").removeEventListener("click", clickEventHandler);
 
   iframe.onload =
-    function(aEvent) { SimpleTest.executeSoon(runBodyEditableDocumentTests1); };
+    function() { SimpleTest.executeSoon(runBodyEditableDocumentTests1); };
   iframe.srcdoc = "<body contenteditable>body:</body>";
 }
 
diff --git a/editor/libeditor/tests/test_bug780908.xhtml b/editor/libeditor/tests/test_bug780908.xhtml
index 590316ef46..6bfa306a71 100644
--- a/editor/libeditor/tests/test_bug780908.xhtml
+++ b/editor/libeditor/tests/test_bug780908.xhtml
@@ -46,7 +46,7 @@ adapted from test_bug607584.xhtml by Kent James <kent@caspia.com>
     QueryInterface: ChromeUtils.generateQI(["nsIWebProgressListener",
                                             "nsISupportsWeakReference"]),
 
-    onStateChange(aWebProgress, aRequest, aStateFlags, aStatus)
+    onStateChange(aWebProgress, aRequest, aStateFlags)
     {
         if (aStateFlags & Ci.nsIWebProgressListener.STATE_STOP)
         {
@@ -69,25 +69,23 @@ adapted from test_bug607584.xhtml by Kent James <kent@caspia.com>
     },
   
   
-    onProgressChange(aWebProgress, aRequest,
-                                aCurSelfProgress, aMaxSelfProgress,
-                                aCurTotalProgress, aMaxTotalProgress)
+    onProgressChange()
       {
       },
   
-    onLocationChange(aWebProgress, aRequest, aLocation, aFlags)
+    onLocationChange()
       {
       },
   
-    onStatusChange(aWebProgress, aRequest, aStatus, aMessage)
+    onStatusChange()
       {
       },
   
-    onSecurityChange(aWebProgress, aRequest, aState)
+    onSecurityChange()
       {
       },
 
-    onContentBlockingEvent(aWebProgress, aRequest, aEvent)
+    onContentBlockingEvent()
       {
       },
 
diff --git a/editor/libeditor/tests/test_command_state_when_readonly.html b/editor/libeditor/tests/test_command_state_when_readonly.html
new file mode 100644
index 0000000000..7b4daaa1b3
--- /dev/null
+++ b/editor/libeditor/tests/test_command_state_when_readonly.html
@@ -0,0 +1,149 @@
+<!doctype html>
+<title>Test for nsIEditor.isCommandEnabled for normal and read-only editors</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<link rel="stylesheet" href="/tests/SimpleTest/test.css">
+<div contenteditable></div>
+<script>
+  let node = document.querySelector("div");
+  node.focus();
+  let htmlEditor =
+    SpecialPowers.wrap(window).docShell.editingSession.getEditorForWindow(window);
+
+  // Supported environments for each command. Supported values for each
+  // environment property:
+  //   content: "empty", "non-empty", "cleared"
+  //   selected: true, false
+  //   readonly: true, false
+  //
+  // If an environment definition does not state a certain property, the command
+  // supports all possible values for that property. The following definition:
+  //    "cmd_copy": [{content: "non-empty", selected: true}],
+  // is equivalent to:
+  //    "cmd_copy": [
+  //      {content: "non-empty", selected: true, readonly: true},
+  //      {content: "non-empty", selected: true, readonly: false},
+  //    ],
+  const TEST_COMMANDS = {
+    "cmd_selectAll": [{content: "non-empty"}],
+
+    "cmd_copy": [{content: "non-empty", selected: true}],
+
+    "cmd_cut": [{content: "non-empty", selected: true, readonly: false}],
+    "cmd_delete": [{content: "non-empty", selected: true, readonly: false}],
+    "cmd_removeList":[{content: "non-empty", selected: true, readonly: false}],
+
+    "cmd_undo": [{content: "cleared", readonly: false}],
+    "cmd_redo": [{content: "cleared", readonly: false}],
+
+    "cmd_switchTextDirection": [{readonly: false}],
+    "cmd_bold": [{readonly: false}],
+    "cmd_italic": [{readonly: false}],
+    "cmd_underline": [{readonly: false}],
+    "cmd_em": [{readonly: false}],
+    "cmd_strong": [{readonly: false}],
+    "cmd_strikethrough": [{readonly: false}],
+    "cmd_superscript": [{readonly: false}],
+    "cmd_subscript": [{readonly: false}],
+    "cmd_indent": [{readonly: false}],
+    "cmd_outdent": [{readonly: false}],
+    "cmd_formatBlock": [{readonly: false}],
+    "cmd_paragraphState": [{readonly: false}],
+    "cmd_fontFace": [{readonly: false}],
+    "cmd_fontSize": [{readonly: false}],
+    "cmd_fontColor": [{readonly: false}],
+    "cmd_backgroundColor": [{readonly: false}],
+    "cmd_highlight": [{readonly: false}],
+    "cmd_align": [{readonly: false}],
+    "cmd_removeStyles": [{readonly: false}],
+    "cmd_increaseFont": [{readonly: false}],
+    "cmd_decreaseFont": [{readonly: false}],
+    "cmd_insertHR": [{readonly: false}],
+    "cmd_insertHTML": [{readonly: false}],
+    "cmd_insertText": [{readonly: false}],
+    "cmd_insertParagraph": [{readonly: false}],
+    "cmd_insertLineBreak": [{readonly: false}],
+    "cmd_tt":[{readonly: false}],
+    "cmd_nobreak":[{readonly: false}],
+    "cmd_cite":[{readonly: false}],
+    "cmd_abbr":[{readonly: false}],
+    "cmd_acronym":[{readonly: false}],
+    "cmd_code":[{readonly: false}],
+    "cmd_samp":[{readonly: false}],
+    "cmd_var":[{readonly: false}],
+    "cmd_removeLinks":[{readonly: false}],
+    "cmd_ol":[{readonly: false}],
+    "cmd_ul":[{readonly: false}],
+    "cmd_dt":[{readonly: false}],
+    "cmd_dd":[{readonly: false}],
+
+    // InsertTagCommand
+    "cmd_insertImageNoUI": [{readonly: false}],
+    "cmd_insertLinkNoUI": [{readonly: false}],
+  };
+
+  function testCommands(content) {
+    for (let readonly of [true, false]){
+      if (readonly) {
+        htmlEditor.flags |= SpecialPowers.Ci.nsIEditor.eEditorReadonlyMask;
+      } else {
+        htmlEditor.flags &= ~SpecialPowers.Ci.nsIEditor.eEditorReadonlyMask;
+      }
+
+      for (let selected of [true, false]) {
+        let selection = window.getSelection();
+        selection.collapse(node);
+
+        if (selected) {
+          if (content == "non-empty") {
+            // The command cmd_removeList needs selected text inside a list. It
+            // does not matter for all other commands, so lets just select that.
+            let range = document.createRange();
+            let li = document.querySelector("li");
+            range.selectNodeContents(li);
+            selection.removeAllRanges();
+            selection.addRange(range);
+          } else {
+            document.execCommand("selectAll");
+          }
+        }
+
+        for (let [cmd, supports] of Object.entries(TEST_COMMANDS)) {
+          // Check if the command should support this environment.
+          let expected = supports.some(supported =>
+            content == (supported?.content ?? content) &&
+            readonly == (supported?.readonly ?? readonly) &&
+            selected == (supported?.selected ?? selected)
+          )
+          is(
+            SpecialPowers.isCommandEnabled(window, cmd),
+            expected,
+            `Enabled state of command ${cmd} should be ${
+              expected ? "TRUE" : "FALSE"
+            } for ${JSON.stringify({content, selected, readonly})}`
+          );
+        }
+      }
+    }
+  }
+
+  testCommands("empty");
+
+  // The cmd_removeList command needs a list.
+  node.innerHTML = "<ul><li><span>abcd</span></li></ul>";
+  testCommands("non-empty");
+
+  // Make some content modifications to enable undo and redo.
+  node.innerText = "ABC";
+  is(node.innerText.trim(), "ABC", "phase 1");
+  document.execCommand("selectAll");
+  synthesizeKey("KEY_Backspace");
+  is(node.innerText.trim(), "", "phase 2");
+  synthesizeKey("3");
+  is(node.innerText.trim(), "3", "phase 3");
+  SpecialPowers.doCommand(window, "cmd_undo");
+  is(node.innerText.trim(), "", "phase 4");
+
+  node.innerHTML = "";
+  testCommands("cleared");
+</script>
diff --git a/editor/libeditor/tests/test_composition_with_highlight_in_texteditor.html b/editor/libeditor/tests/test_composition_with_highlight_in_texteditor.html
index d6bb703231..0990d87adb 100644
--- a/editor/libeditor/tests/test_composition_with_highlight_in_texteditor.html
+++ b/editor/libeditor/tests/test_composition_with_highlight_in_texteditor.html
@@ -23,9 +23,9 @@ SimpleTest.waitForFocus(() => {
   );
   const editActionListener = {
     QueryInterface: SpecialPowers.ChromeUtils.generateQI(["nsIEditActionListener"]),
-    WillDeleteText: (textNode, offset, length) => {},
-    DidInsertText: (textNode, offset, aString) => {},
-    WillDeleteRanges: (rangesToDelete) => {},
+    WillDeleteText: () => {},
+    DidInsertText: () => {},
+    WillDeleteRanges: () => {},
   };
   // Highlight "a"
   findSelection.setBaseAndExtent(
diff --git a/editor/libeditor/tests/test_contenteditable_text_input_handling.html b/editor/libeditor/tests/test_contenteditable_text_input_handling.html
index c00056a0f0..13a00a65b8 100644
--- a/editor/libeditor/tests/test_contenteditable_text_input_handling.html
+++ b/editor/libeditor/tests/test_contenteditable_text_input_handling.html
@@ -34,8 +34,7 @@ function runTests() {
       aEvent.preventDefault(); // prevent the browser default behavior
     },
   };
-  var els = Services.els;
-  els.addSystemEventListener(window, "keypress", listener, false);
+  SpecialPowers.wrap(window).addEventListener("keypress", listener, { mozSystemGroup: true });
 
   var staticContent = document.getElementById("static");
   staticContent._defaultValue = getTextValue(staticContent);
@@ -306,7 +305,7 @@ function runTests() {
   testTextInput(inputInEditor);
   testTextInput(textareaInEditor);
 
-  els.removeSystemEventListener(window, "keypress", listener, false);
+  SpecialPowers.wrap(window).removeEventListener("keypress", listener, { mozSystemGroup: true });
 
   SimpleTest.finish();
 }
diff --git a/editor/libeditor/tests/test_dragdrop.html b/editor/libeditor/tests/test_dragdrop.html
index 6295661faa..5c7d940928 100644
--- a/editor/libeditor/tests/test_dragdrop.html
+++ b/editor/libeditor/tests/test_dragdrop.html
@@ -3101,7 +3101,7 @@ async function doTest() {
     beforeinputEvents = [];
     inputEvents = [];
     dragEvents = [];
-    const onDragStart = aEvent => {
+    const onDragStart = () => {
       input.style.display = "none";
       document.documentElement.scrollTop;
       input.style.display = "";
@@ -3147,7 +3147,7 @@ async function doTest() {
     beforeinputEvents = [];
     inputEvents = [];
     dragEvents = [];
-    const onDragStart = aEvent => {
+    const onDragStart = () => {
       textarea.style.display = "none";
       document.documentElement.scrollTop;
       textarea.style.display = "";
@@ -3193,13 +3193,13 @@ async function doTest() {
     beforeinputEvents = [];
     inputEvents = [];
     dragEvents = [];
-    const onMouseMove = aEvent => {
+    const onMouseMove = () => {
       input.style.display = "none";
       document.documentElement.scrollTop;
       input.style.display = "";
       document.documentElement.scrollTop;
     };
-    const onMouseDown = aEvent => {
+    const onMouseDown = () => {
       document.addEventListener("mousemove", onMouseMove, {once: true});
     }
     const onDrop = aEvent => {
@@ -3243,13 +3243,13 @@ async function doTest() {
     beforeinputEvents = [];
     inputEvents = [];
     dragEvents = [];
-    const onMouseMove = aEvent => {
+    const onMouseMove = () => {
       textarea.style.display = "none";
       document.documentElement.scrollTop;
       textarea.style.display = "";
       document.documentElement.scrollTop;
     };
-    const onMouseDown = aEvent => {
+    const onMouseDown = () => {
       document.addEventListener("mousemove", onMouseMove, {once: true});
     }
     const onDrop = aEvent => {
diff --git a/editor/libeditor/tests/test_execCommandPaste_noTarget.html b/editor/libeditor/tests/test_execCommandPaste_noTarget.html
index 6586ca768d..70de112a78 100644
--- a/editor/libeditor/tests/test_execCommandPaste_noTarget.html
+++ b/editor/libeditor/tests/test_execCommandPaste_noTarget.html
@@ -32,7 +32,7 @@
 
     // Check that reading text from the clipboard in non-privileged contexts
     // still doesn't work.
-    function onpstfail(e) {
+    function onpstfail() {
       ok(false, "Should not see paste event triggered by non-privileged call");
     }
     document.addEventListener("paste", onpstfail);
diff --git a/editor/libeditor/tests/test_htmleditor_keyevent_handling.html b/editor/libeditor/tests/test_htmleditor_keyevent_handling.html
index 58666beb35..6fb79212e2 100644
--- a/editor/libeditor/tests/test_htmleditor_keyevent_handling.html
+++ b/editor/libeditor/tests/test_htmleditor_keyevent_handling.html
@@ -79,8 +79,8 @@ async function runTests() {
        getDesciption(aPreventedOnBubbling) + "prevented on bubbling phase");
   }
 
-  SpecialPowers.addSystemEventListener(window, "keypress", listener, true);
-  SpecialPowers.addSystemEventListener(window, "keypress", listener, false);
+  SpecialPowers.wrap(window).addEventListener("keypress", listener, { capture: true, mozSystemGroup: true });
+  SpecialPowers.wrap(window).addEventListener("keypress", listener, { capture: false, mozSystemGroup: true });
 
   // eslint-disable-next-line complexity
   async function doTest(
@@ -754,8 +754,8 @@ async function runTests() {
   await doTest(htmlEditor, "readonly and non-tabbable HTML editor but plaintext mode",
          true, false, true);
 
-  SpecialPowers.removeSystemEventListener(window, "keypress", listener, true);
-  SpecialPowers.removeSystemEventListener(window, "keypress", listener, false);
+  SpecialPowers.wrap(window).removeEventListener("keypress", listener, { capture: true, mozSystemGroup: true });
+  SpecialPowers.wrap(window).removeEventListener("keypress", listener, { capture: false, mozSystemGroup: true });
 
   SimpleTest.finish();
 }
diff --git a/editor/libeditor/tests/test_middle_click_paste.html b/editor/libeditor/tests/test_middle_click_paste.html
index eaa918c194..d34411e54b 100644
--- a/editor/libeditor/tests/test_middle_click_paste.html
+++ b/editor/libeditor/tests/test_middle_click_paste.html
@@ -224,7 +224,7 @@ async function doTextareaTests(aTextarea) {
   aTextarea.value = "";
 
   let pasteEventCount = 0;
-  function pasteEventLogger(event) {
+  function pasteEventLogger() {
     pasteEventCount++;
   }
   aTextarea.addEventListener("paste", pasteEventLogger);
@@ -381,7 +381,7 @@ async function doContenteditableTests(aEditableDiv) {
   aEditableDiv.innerHTML = "";
 
   let pasteEventCount = 0;
-  function pasteEventLogger(event) {
+  function pasteEventLogger() {
     pasteEventCount++;
   }
   aEditableDiv.addEventListener("paste", pasteEventLogger);
diff --git a/editor/libeditor/tests/test_nsIEditor_documentIsEmpty.html b/editor/libeditor/tests/test_nsIEditor_documentIsEmpty.html
index 49c1db78a9..1e60e58191 100644
--- a/editor/libeditor/tests/test_nsIEditor_documentIsEmpty.html
+++ b/editor/libeditor/tests/test_nsIEditor_documentIsEmpty.html
@@ -80,7 +80,7 @@
           ok(true, "nsIEditor.documentIsEmpty should throw an exception when no editing host has focus");
         }
         document.querySelector("div[contenteditable]").focus();
-        todo_is(getHTMLEditor().documentIsEmpty, true,
+        is(getHTMLEditor().documentIsEmpty, true,
           "nsIEditor.documentIsEmpty should be true when editing host does not have contents");
 
         document.body.innerHTML = "<div contenteditable><br></div>";
diff --git a/editor/libeditor/tests/test_paste_redirect_focus_in_paste_event_listener.html b/editor/libeditor/tests/test_paste_redirect_focus_in_paste_event_listener.html
index b82938158e..89d7531fa5 100644
--- a/editor/libeditor/tests/test_paste_redirect_focus_in_paste_event_listener.html
+++ b/editor/libeditor/tests/test_paste_redirect_focus_in_paste_event_listener.html
@@ -57,7 +57,7 @@ SimpleTest.waitForFocus(async () => {
       const editableElementDesc = `<${
         editableElement.tagName.toLocaleLowerCase()
       }${editableElement.hasAttribute("contenteditable") ? " contenteditable" : ""}>`;
-      (test_from_editableElement_to_input => {
+      (() => {
         const input = document.querySelector("#dest > input");
         editableElement.focus();
         editableElement.addEventListener(
@@ -84,7 +84,7 @@ SimpleTest.waitForFocus(async () => {
         input.value = "";
       })();
 
-      (test_from_editableElement_to_contenteditable => {
+      (() => {
         const contentEditable = document.querySelector("#dest > div[contenteditable]");
         editableElement.focus();
         editableElement.addEventListener(
@@ -111,7 +111,7 @@ SimpleTest.waitForFocus(async () => {
         contentEditable.innerHTML = "<br>";
       })();
 
-      (test_from_editableElement_to_non_editable => {
+      (() => {
         const button = document.querySelector("#dest > button");
         editableElement.focus();
         editableElement.addEventListener(
diff --git a/editor/libeditor/tests/test_texteditor_keyevent_handling.html b/editor/libeditor/tests/test_texteditor_keyevent_handling.html
index 2c80181b3c..6b3d5f4608 100644
--- a/editor/libeditor/tests/test_texteditor_keyevent_handling.html
+++ b/editor/libeditor/tests/test_texteditor_keyevent_handling.html
@@ -80,10 +80,8 @@ async function runTests() {
   }
 
   var parentElement = document.getElementById("display");
-  SpecialPowers.addSystemEventListener(parentElement, "keypress", listener,
-                                       true);
-  SpecialPowers.addSystemEventListener(parentElement, "keypress", listener,
-                                       false);
+  SpecialPowers.wrap(parentElement).addEventListener("keypress", listener, { capture: true, mozSystemGroup: true });
+  SpecialPowers.wrap(parentElement).addEventListener("keypress", listener, { capture: false, mozSystemGroup: true });
 
   async function doTest(aElement, aDescription, aIsSingleLine, aIsReadonly) {
     function reset(aText) {
@@ -457,10 +455,8 @@ async function runTests() {
   textarea.setAttribute("readonly", "readonly");
   await doTest(textarea, "<textarea readonly>", false, true);
 
-  SpecialPowers.removeSystemEventListener(parentElement, "keypress", listener,
-                                          true);
-  SpecialPowers.removeSystemEventListener(parentElement, "keypress", listener,
-                                          false);
+  SpecialPowers.wrap(parentElement).removeEventListener("keypress", listener, { capture: true, mozSystemGroup: true });
+  SpecialPowers.wrap(parentElement).removeEventListener("keypress", listener, { capture: false, mozSystemGroup: true });
 
   SimpleTest.finish();
 }
diff --git a/editor/libeditor/tests/test_texteditor_wrapping_long_line.html b/editor/libeditor/tests/test_texteditor_wrapping_long_line.html
index 14a445bbb0..013e563a27 100644
--- a/editor/libeditor/tests/test_texteditor_wrapping_long_line.html
+++ b/editor/libeditor/tests/test_texteditor_wrapping_long_line.html
@@ -11,7 +11,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1733878
   <script src="/tests/SimpleTest/EventUtils.js"></script>
   <script>
   /** Test for bug 1733878 **/
-  window.addEventListener("DOMContentLoaded", (event) => {
+  window.addEventListener("DOMContentLoaded", () => {
     SimpleTest.waitForExplicitFinish();
     SimpleTest.waitForFocus(function() {
       document.body.textContent = ""; // It would be \n\n otherwise...
diff --git a/editor/reftests/reftest.list b/editor/reftests/reftest.list
index f09ad54b1c..9dc51429bd 100644
--- a/editor/reftests/reftest.list
+++ b/editor/reftests/reftest.list
@@ -93,8 +93,8 @@ skip-if(Android) needs-focus == spellcheck-non-latin-japanese.html spellcheck-no
 skip-if(Android) fuzzy(0-3,0-1) needs-focus == spellcheck-non-latin-korean.html spellcheck-non-latin-korean-ref.html
 == unneeded_scroll.html unneeded_scroll-ref.html
 == caret_on_presshell_reinit.html caret_on_presshell_reinit-ref.html
-fuzzy-if(browserIsRemote,0-255,0-3) asserts-if(browserIsRemote,0-3) == caret_on_presshell_reinit-2.html caret_on_presshell_reinit-ref.html # bug 959132 for assertions
-fuzzy-if(asyncPan&&!layersGPUAccelerated,0-102,0-2824) == 642800.html 642800-ref.html
+fuzzy(0-255,0-3) asserts(0-3) == caret_on_presshell_reinit-2.html caret_on_presshell_reinit-ref.html # bug 959132 for assertions
+== 642800.html 642800-ref.html
 needs-focus == selection_visibility_after_reframe.html selection_visibility_after_reframe-ref.html
 needs-focus != selection_visibility_after_reframe-2.html selection_visibility_after_reframe-ref.html
 needs-focus != selection_visibility_after_reframe-3.html selection_visibility_after_reframe-ref.html
@@ -115,8 +115,8 @@ needs-focus == 462758-grabbers-resizers.html 462758-grabbers-resizers-ref.html
 skip-if(Android) needs-focus == spellcheck-superscript-1.html spellcheck-superscript-1-ref.html
 skip-if(Android) needs-focus != spellcheck-superscript-2.html spellcheck-superscript-2-ref.html
 fuzzy(0-1,0-3400) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-1.html 824080-1-ref.html
-fuzzy-if(OSX,0-1,0-1) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-2.html 824080-2-ref.html #Bug 1313253
-fuzzy-if(OSX,0-1,0-1) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-3.html 824080-3-ref.html #Bug 1312951
+fuzzy-if(cocoaWidget,0-1,0-1) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-2.html 824080-2-ref.html #Bug 1313253
+fuzzy-if(cocoaWidget,0-1,0-1) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-3.html 824080-3-ref.html #Bug 1312951
 needs-focus != 824080-2.html 824080-3.html
 fuzzy(0-1,0-3200) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-4.html 824080-4-ref.html
 fuzzy(0-2,0-1800) needs-focus pref(layout.accessiblecaret.enabled,false) pref(layout.accessiblecaret.enabled_on_touch,false) == 824080-5.html 824080-5-ref.html
diff --git a/editor/spellchecker/tests/test_spellcheck_after_edit.html b/editor/spellchecker/tests/test_spellcheck_after_edit.html
index 24806addee..7c3f656855 100644
--- a/editor/spellchecker/tests/test_spellcheck_after_edit.html
+++ b/editor/spellchecker/tests/test_spellcheck_after_edit.html
@@ -67,11 +67,11 @@ SimpleTest.waitForFocus(async () => {
           normalSel.collapse(editingHost.querySelector("p + p").firstChild, 0);
           return 0;
         },
-        run: (editingHost) => {
+        run: () => {
           document.execCommand("delete");
           return 0;
         },
-        check: (spellCheckSel, editingHost) => {
+        check: (spellCheckSel) => {
           is(
             spellCheckSel.rangeCount,
             0,
@@ -86,11 +86,11 @@ SimpleTest.waitForFocus(async () => {
           normalSel.collapse(editingHost.querySelector("p + p").firstChild, 0);
           return 2;
         },
-        run: (editingHost) => {
+        run: () => {
           document.execCommand("delete");
           return 0;
         },
-        check: (spellCheckSel, editingHost) => {
+        check: (spellCheckSel) => {
           is(
             spellCheckSel.rangeCount,
             0,
@@ -105,11 +105,11 @@ SimpleTest.waitForFocus(async () => {
           normalSel.collapse(editingHost.querySelector("p").firstChild, "It is".length);
           return 1;
         },
-        run: (editingHost) => {
+        run: () => {
           document.execCommand("insertParagraph");
           return 0;
         },
-        check: (spellCheckSel, editingHost) => {
+        check: (spellCheckSel) => {
           is(
             spellCheckSel.rangeCount,
             0,
@@ -124,7 +124,7 @@ SimpleTest.waitForFocus(async () => {
           normalSel.collapse(editingHost.querySelector("p").firstChild, "It's beco".length);
           return 0;
         },
-        run: (editingHost) => {
+        run: () => {
           document.execCommand("insertParagraph");
           return 1;
         },