--- a/editor/libeditor/HTMLEditSubActionHandler.cpp
+++ b/editor/libeditor/HTMLEditSubActionHandler.cpp
@@ -2591,39 +2591,42 @@ EditActionResult HTMLEditor::HandleDelet
         "HTMLEditor::HandleDeleteCollapsedSelectionAtAtomicContent() failed");
     return result;
   }
 
   if (scanFromStartPointResult.ReachedOtherBlockElement()) {
     if (NS_WARN_IF(!scanFromStartPointResult.GetContent()->IsElement())) {
       return EditActionResult(NS_ERROR_FAILURE);
     }
+    AutoBlockElementsJoiner joiner;
+    if (!joiner.PrepareToDeleteCollapsedSelectionAtOtherBlockBoundary(
+            *this, aDirectionAndAmount, *scanFromStartPointResult.ElementPtr(),
+            startPoint, wsRunScanner)) {
+      return EditActionCanceled();
+    }
     EditActionResult result =
-        HandleDeleteCollapsedSelectionAtOtherBlockBoundary(
-            aDirectionAndAmount, aStripWrappers,
-            MOZ_KnownLive(*scanFromStartPointResult.ElementPtr()), startPoint,
-            wsRunScanner);
-    NS_WARNING_ASSERTION(
-        result.Succeeded(),
-        "HTMLEditor::HandleDeleteCollapsedSelectionAtOtherBlockBoundary() "
-        "failed");
+        joiner.Run(*this, aDirectionAndAmount, aStripWrappers, startPoint);
+    NS_WARNING_ASSERTION(result.Succeeded(),
+                         "HTMLEditor::AutoBlockElementsJoiner::Run() failed "
+                         "(other block boundary)");
     return result;
   }
 
   if (scanFromStartPointResult.ReachedCurrentBlockBoundary()) {
     if (NS_WARN_IF(!scanFromStartPointResult.GetContent()->IsElement())) {
       return EditActionResult(NS_ERROR_FAILURE);
     }
     AutoBlockElementsJoiner joiner;
     if (!joiner.PrepareToDeleteCollapsedSelectionAtCurrentBlockBoundary(
             *this, aDirectionAndAmount, *scanFromStartPointResult.ElementPtr(),
             startPoint)) {
       return EditActionCanceled();
     }
-    EditActionResult result = joiner.Run(*this, startPoint);
+    EditActionResult result =
+        joiner.Run(*this, aDirectionAndAmount, aStripWrappers, startPoint);
     NS_WARNING_ASSERTION(result.Succeeded(),
                          "HTMLEditor::AutoBlockElementsJoiner::Run() failed "
                          "(current block boundary)");
     return result;
   }
 
   MOZ_ASSERT_UNREACHABLE("New type of reached content hasn't been handled yet");
   return EditActionIgnored();
@@ -3022,140 +3025,166 @@ EditActionResult HTMLEditor::HandleDelet
       EditorBase::GetStartPoint(*SelectionRefPtr()));
   NS_WARNING_ASSERTION(
       NS_SUCCEEDED(rv),
       "HTMLEditor::InsertBRElementIfHardLineIsEmptyAndEndsWithBlockBoundary() "
       "failed");
   return EditActionHandled(rv);
 }
 
-EditActionResult HTMLEditor::HandleDeleteCollapsedSelectionAtOtherBlockBoundary(
-    nsIEditor::EDirection aDirectionAndAmount,
-    nsIEditor::EStripWrappers aStripWrappers, Element& aOtherBlockElement,
-    const EditorDOMPoint& aCaretPoint, WSRunScanner& aWSRunScannerAtCaret) {
-  MOZ_ASSERT(IsEditActionDataAvailable());
-  MOZ_ASSERT(aCaretPoint.IsSet());
+bool HTMLEditor::AutoBlockElementsJoiner::
+    PrepareToDeleteCollapsedSelectionAtOtherBlockBoundary(
+        const HTMLEditor& aHTMLEditor,
+        nsIEditor::EDirection aDirectionAndAmount, Element& aOtherBlockElement,
+        const EditorDOMPoint& aCaretPoint,
+        const WSRunScanner& aWSRunScannerAtCaret) {
+  MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
+  MOZ_ASSERT(aCaretPoint.IsSetAndValid());
+
+  mMode = Mode::JoinOtherBlock;
 
   // Make sure it's not a table element.  If so, cancel the operation
   // (translation: users cannot backspace or delete across table cells)
   if (HTMLEditUtils::IsAnyTableElement(&aOtherBlockElement)) {
-    return EditActionCanceled();
+    return false;
   }
 
   // Next to a block.  See if we are between a block and a br.  If so, we
   // really want to delete the br.  Else join content at selection to the
   // block.
   WSScanResult scanFromCaretResult =
       aDirectionAndAmount == nsIEditor::eNext
           ? aWSRunScannerAtCaret.ScanPreviousVisibleNodeOrBlockBoundaryFrom(
                 aCaretPoint)
           : aWSRunScannerAtCaret.ScanNextVisibleNodeOrBlockBoundaryFrom(
                 aCaretPoint);
 
   // First find the adjacent node in the block
-  nsCOMPtr<nsIContent> leafNode;
-  nsCOMPtr<nsINode> leftNode, rightNode;
   if (aDirectionAndAmount == nsIEditor::ePrevious) {
-    leafNode = GetLastEditableLeaf(aOtherBlockElement);
-    leftNode = leafNode;
-    rightNode = aCaretPoint.GetContainer();
+    mLeafContentInOtherBlock =
+        aHTMLEditor.GetLastEditableLeaf(aOtherBlockElement);
+    mLeftContent = mLeafContentInOtherBlock;
+    mRightContent = aCaretPoint.GetContainerAsContent();
   } else {
-    leafNode = GetFirstEditableLeaf(aOtherBlockElement);
-    leftNode = aCaretPoint.GetContainer();
-    rightNode = leafNode;
-  }
-
-  bool didBRElementDeleted = false;
+    mLeafContentInOtherBlock =
+        aHTMLEditor.GetFirstEditableLeaf(aOtherBlockElement);
+    mLeftContent = aCaretPoint.GetContainerAsContent();
+    mRightContent = mLeafContentInOtherBlock;
+  }
+
+  // If we found a `<br>` element, we need to delete it instead of joining the
+  // contents.
   if (scanFromCaretResult.ReachedBRElement()) {
-    nsresult rv = DeleteNodeWithTransaction(
-        MOZ_KnownLive(*scanFromCaretResult.BRElementPtr()));
-    if (NS_WARN_IF(Destroyed())) {
+    mBRElement = scanFromCaretResult.BRElementPtr();
+    return true;
+  }
+
+  return mLeftContent && mRightContent;
+}
+
+EditActionResult HTMLEditor::AutoBlockElementsJoiner::
+    HandleDeleteCollapsedSelectionAtOtherBlockBoundary(
+        HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
+        nsIEditor::EStripWrappers aStripWrappers,
+        const EditorDOMPoint& aCaretPoint) {
+  MOZ_ASSERT(aHTMLEditor.IsEditActionDataAvailable());
+  MOZ_ASSERT(aCaretPoint.IsSetAndValid());
+
+  // If we found a `<br>` element, we should delete it instead of joinning the
+  // contents.
+  if (mBRElement) {
+    nsresult rv =
+        aHTMLEditor.DeleteNodeWithTransaction(MOZ_KnownLive(*mBRElement));
+    if (NS_WARN_IF(aHTMLEditor.Destroyed())) {
       return EditActionResult(NS_ERROR_EDITOR_DESTROYED);
     }
     if (NS_FAILED(rv)) {
       NS_WARNING("HTMLEditor::DeleteNodeWithTransaction() failed");
       return EditActionResult(rv);
     }
-    didBRElementDeleted = true;
-  }
-
-  // Don't cross table boundaries
-  if (leftNode && rightNode &&
-      HTMLEditor::NodesInDifferentTableElements(*leftNode, *rightNode)) {
-    // If we have not deleted `<br>` element and are not called recursively,
-    // we should call `DeleteSelectionWithTransaction()` here, but we cannot
-    // detect it for now.  Therefore, we should just tell the caller of that
-    // we does nothing.
-    return didBRElementDeleted ? EditActionHandled() : EditActionIgnored();
-  }
-
-  if (didBRElementDeleted) {
+
+    if (mLeftContent && mRightContent &&
+        HTMLEditor::NodesInDifferentTableElements(*mLeftContent,
+                                                  *mRightContent)) {
+      return EditActionHandled();
+    }
+
     // Put selection at edge of block and we are done.
-    if (NS_WARN_IF(!leafNode)) {
+    if (NS_WARN_IF(!mLeafContentInOtherBlock)) {
+      // XXX This must be odd case.  The other block can be empty.
       return EditActionHandled(NS_ERROR_FAILURE);
     }
-    EditorDOMPoint newSel =
-        GetGoodCaretPointFor(*leafNode, aDirectionAndAmount);
-    if (!newSel.IsSet()) {
+    EditorDOMPoint newCaretPosition = aHTMLEditor.GetGoodCaretPointFor(
+        *mLeafContentInOtherBlock, aDirectionAndAmount);
+    if (!newCaretPosition.IsSet()) {
       NS_WARNING("HTMLEditor::GetGoodCaretPointFor() failed");
       return EditActionHandled(NS_ERROR_FAILURE);
     }
-    nsresult rv = CollapseSelectionTo(newSel);
+    rv = aHTMLEditor.CollapseSelectionTo(newCaretPosition);
     if (NS_WARN_IF(rv == NS_ERROR_EDITOR_DESTROYED)) {
       return EditActionHandled(NS_ERROR_EDITOR_DESTROYED);
     }
     NS_WARNING_ASSERTION(
         NS_SUCCEEDED(rv),
         "HTMLEditor::CollapseSelectionTo() failed, but ignored");
     return EditActionHandled();
   }
 
+  MOZ_ASSERT(mLeftContent);
+  MOZ_ASSERT(mRightContent);
+
+  if (HTMLEditor::NodesInDifferentTableElements(*mLeftContent,
+                                                *mRightContent)) {
+    // If we have not deleted `<br>` element and are not called recursively,
+    // we should call `DeleteSelectionWithTransaction()` here, but we cannot
+    // detect it for now.  Therefore, we should just tell the caller of that
+    // we does nothing.
+    return EditActionIgnored();
+  }
+
   // Else we are joining content to block
   EditActionResult result(NS_OK);
   EditorDOMPoint pointToPutCaret(aCaretPoint);
   {
-    AutoTrackDOMPoint tracker(RangeUpdaterRef(), &pointToPutCaret);
-    if (NS_WARN_IF(!leftNode) || NS_WARN_IF(!leftNode->IsContent()) ||
-        NS_WARN_IF(!rightNode) || NS_WARN_IF(!rightNode->IsContent())) {
-      return EditActionResult(NS_ERROR_FAILURE);
-    }
-    result |=
-        TryToJoinBlocksWithTransaction(MOZ_KnownLive(*leftNode->AsContent()),
-                                       MOZ_KnownLive(*rightNode->AsContent()));
+    AutoTrackDOMPoint tracker(aHTMLEditor.RangeUpdaterRef(), &pointToPutCaret);
+    result |= aHTMLEditor.TryToJoinBlocksWithTransaction(
+        MOZ_KnownLive(*mLeftContent), MOZ_KnownLive(*mRightContent));
     if (result.Failed()) {
       NS_WARNING("HTMLEditor::TryToJoinBlocksWithTransaction() failed");
       return result;
     }
   }
 
   // If TryToJoinBlocksWithTransaction() didn't handle it and it's not
   // canceled, user may want to modify the start leaf node or the last leaf
   // node of the block.
   if (!result.Handled() && !result.Canceled() &&
-      leafNode != aCaretPoint.GetContainer()) {
-    int32_t offset = aDirectionAndAmount == nsIEditor::ePrevious
-                         ? static_cast<int32_t>(leafNode->Length())
-                         : 0;
-    nsresult rv = CollapseSelectionTo(EditorRawDOMPoint(leafNode, offset));
+      mLeafContentInOtherBlock != aCaretPoint.GetContainer()) {
+    int32_t offset =
+        aDirectionAndAmount == nsIEditor::ePrevious
+            ? static_cast<int32_t>(mLeafContentInOtherBlock->Length())
+            : 0;
+    nsresult rv = aHTMLEditor.CollapseSelectionTo(
+        EditorRawDOMPoint(mLeafContentInOtherBlock, offset));
     if (NS_WARN_IF(rv == NS_ERROR_EDITOR_DESTROYED)) {
       return result.SetResult(NS_ERROR_EDITOR_DESTROYED);
     }
     NS_WARNING_ASSERTION(
         NS_SUCCEEDED(rv),
         "HTMLEditor::CollapseSelectionTo() failed, but ignored");
-    EditActionResult result =
-        HandleDeleteSelectionInternal(aDirectionAndAmount, aStripWrappers);
+    EditActionResult result = aHTMLEditor.HandleDeleteSelectionInternal(
+        aDirectionAndAmount, aStripWrappers);
     NS_WARNING_ASSERTION(
         result.Succeeded(),
         "Recursive HTMLEditor::HandleDeleteSelectionInternal() failed");
     return result;
   }
 
   // Otherwise, we must have deleted the selection as user expected.
-  nsresult rv = CollapseSelectionTo(pointToPutCaret);
+  nsresult rv = aHTMLEditor.CollapseSelectionTo(pointToPutCaret);
   if (NS_WARN_IF(rv == NS_ERROR_EDITOR_DESTROYED)) {
     return result.SetResult(NS_ERROR_EDITOR_DESTROYED);
   }
   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                        "HTMLEditor::CollapseSelectionTo() failed, but ignored");
   return result;
 }
 

--- a/editor/libeditor/HTMLEditor.h
+++ b/editor/libeditor/HTMLEditor.h
@@ -2697,51 +2697,94 @@ class HTMLEditor final : public TextEdit
      *                                  deletion.
      */
     bool PrepareToDeleteCollapsedSelectionAtCurrentBlockBoundary(
         const HTMLEditor& aHTMLEditor,
         nsIEditor::EDirection aDirectionAndAmount,
         Element& aCurrentBlockElement, const EditorDOMPoint& aCaretPoint);
 
     /**
+     * PrepareToDeleteCollapsedSelectionAtOtherBlockBoundary() considers
+     * left content and right content which are joined for handling deletion at
+     * other block boundary (i.e., immediately before or after a block).
+     *
+     * @param aHTMLEditor               The HTML editor.
+     * @param aDirectionAndAmount       Direction of the deletion.
+     * @param aOtherBlockElement        The block element which follows the
+     *                                  caret or is followed by caret.
+     * @param aCaretPoint               The caret point (i.e., selection start
+     *                                  or end).
+     * @param aWSRunScannerAtCaret      WSRunScanner instance which was
+     *                                  initialized with the caret point.
+     * @return                          true if can continue to handle the
+     *                                  deletion.
+     */
+    bool PrepareToDeleteCollapsedSelectionAtOtherBlockBoundary(
+        const HTMLEditor& aHTMLEditor,
+        nsIEditor::EDirection aDirectionAndAmount, Element& aOtherBlockElement,
+        const EditorDOMPoint& aCaretPoint,
+        const WSRunScanner& aWSRunScannerAtCaret);
+
+    /**
      * Run() executes the joining.
      *
      * @param aHTMLEditor       The HTML editor.
      * @param aCaretPoint       The caret point (i.e., selection start or end).
      */
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT EditActionResult
-    Run(HTMLEditor& aHTMLEditor, const EditorDOMPoint& aCaretPoint) {
+    Run(HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
+        nsIEditor::EStripWrappers aStripWrappers,
+        const EditorDOMPoint& aCaretPoint) {
       switch (mMode) {
         case Mode::JoinCurrentBlock: {
           EditActionResult result =
               HandleDeleteCollapsedSelectionAtCurrentBlockBoundary(aHTMLEditor,
                                                                    aCaretPoint);
           NS_WARNING_ASSERTION(
               result.Succeeded(),
               "AutoBlockElementsJoiner::"
               "HandleDeleteCollapsedSelectionAtCurrentBlockBoundary() failed");
           return result;
         }
+        case Mode::JoinOtherBlock: {
+          EditActionResult result =
+              HandleDeleteCollapsedSelectionAtOtherBlockBoundary(
+                  aHTMLEditor, aDirectionAndAmount, aStripWrappers,
+                  aCaretPoint);
+          NS_WARNING_ASSERTION(
+              result.Succeeded(),
+              "AutoBlockElementsJoiner::"
+              "HandleDeleteCollapsedSelectionAtOtherBlockBoundary() failed");
+          return result;
+        }
         case Mode::NotInitialized:
           return EditActionIgnored();
       }
       return EditActionResult(NS_ERROR_NOT_INITIALIZED);
     }
 
    private:
     [[nodiscard]] MOZ_CAN_RUN_SCRIPT EditActionResult
     HandleDeleteCollapsedSelectionAtCurrentBlockBoundary(
         HTMLEditor& aHTMLEditor, const EditorDOMPoint& aCaretPoint);
+    [[nodiscard]] MOZ_CAN_RUN_SCRIPT EditActionResult
+    HandleDeleteCollapsedSelectionAtOtherBlockBoundary(
+        HTMLEditor& aHTMLEditor, nsIEditor::EDirection aDirectionAndAmount,
+        nsIEditor::EStripWrappers aStripWrappersconst,
+        const EditorDOMPoint& aCaretPoint);
 
     enum class Mode {
       NotInitialized,
       JoinCurrentBlock,
+      JoinOtherBlock,
     };
     nsCOMPtr<nsIContent> mLeftContent;
     nsCOMPtr<nsIContent> mRightContent;
+    nsCOMPtr<nsIContent> mLeafContentInOtherBlock;
+    RefPtr<dom::HTMLBRElement> mBRElement;
     Mode mMode = Mode::NotInitialized;
   };
 
   /**
    * HandleDeleteCollapsedSelectionAtOtherBlockBoundary() handles deletion at
    * other block boundary (i.e., immediately before or after a block).
    * If this does not join blocks, `WillDeleteSelection()` may be called
    * recursively.

--- a/editor/libeditor/tests/browserscope/lib/richtext2/currentStatus.js
+++ b/editor/libeditor/tests/browserscope/lib/richtext2/currentStatus.js
@@ -1,15 +1,15 @@
 /**
  * The current status of the test suite.
  *
  * See README.Mozilla for details on how to generate this.
  */
 const knownFailures = {
-  "value": {
+  value: {
     "A-Proposed-FS:18px_TEXT-1_SI-dM": true,
     "A-Proposed-FS:18px_TEXT-1_SI-body": true,
     "A-Proposed-FS:18px_TEXT-1_SI-div": true,
     "A-Proposed-FS:large_TEXT-1_SI-dM": true,
     "A-Proposed-FS:large_TEXT-1_SI-body": true,
     "A-Proposed-FS:large_TEXT-1_SI-div": true,
     "A-Proposed-CB:name_TEXT-1_SI-dM": true,
     "A-Proposed-CB:name_TEXT-1_SI-body": true,
@@ -214,18 +214,16 @@ const knownFailures = {
     "D-Proposed-TR3rs:3-1_SO1-div": true,
     "D-Proposed-TR3rs:3-1_SO2-dM": true,
     "D-Proposed-TR3rs:3-1_SO2-body": true,
     "D-Proposed-TR3rs:3-1_SO2-div": true,
     "D-Proposed-TR3rs:3-1_SO3-dM": true,
     "D-Proposed-TR3rs:3-1_SO3-body": true,
     "D-Proposed-TR3rs:3-1_SO3-div": true,
     "D-Proposed-DIV:ce:false-1_SB-dM": true,
-    "D-Proposed-DIV:ce:false-1_SB-body": true,
-    "D-Proposed-DIV:ce:false-1_SB-div": true,
     "D-Proposed-DIV:ce:false-1_SL-dM": true,
     "D-Proposed-DIV:ce:false-1_SL-body": true,
     "D-Proposed-DIV:ce:false-1_SL-div": true,
     "D-Proposed-DIV:ce:false-1_SR-dM": true,
     "D-Proposed-DIV:ce:false-1_SR-body": true,
     "D-Proposed-DIV:ce:false-1_SR-div": true,
     "D-Proposed-DIV:ce:false-1_SI-dM": true,
     "FD-Proposed-OL-LI-1_SW-dM": true,
@@ -457,19 +455,19 @@ const knownFailures = {
     "QV-Proposed-HC_SPANs:bc:b12-SPAN-1_SI-dM": true,
     "QV-Proposed-HC_SPANs:bc:b12-SPAN-1_SI-body": true,
     "QV-Proposed-HC_SPANs:bc:b12-SPAN-1_SI-div": true,
     "QV-Proposed-HC_SPAN.bcred-1_SI-dM": true,
     "QV-Proposed-HC_SPAN.bcred-1_SI-body": true,
     "QV-Proposed-HC_SPAN.bcred-1_SI-div": true,
     "QV-Proposed-HC_MYBCRED-1-SI-dM": true,
     "QV-Proposed-HC_MYBCRED-1-SI-body": true,
-    "QV-Proposed-HC_MYBCRED-1-SI-div": true
+    "QV-Proposed-HC_MYBCRED-1-SI-div": true,
   },
-  "select": {
+  select: {
     "S-Proposed-UNSEL_TEXT-1_SI-dM": true,
     "S-Proposed-UNSEL_TEXT-1_SI-body": true,
     "S-Proposed-UNSEL_TEXT-1_SI-div": true,
     "S-Proposed-SM:m.f.c_TEXT-1_SI-1-dM": true,
     "S-Proposed-SM:m.f.c_TEXT-1_SI-1-body": true,
     "S-Proposed-SM:m.f.c_TEXT-1_SI-1-div": true,
     "S-Proposed-SM:m.b.c_TEXT-1_SI-1-dM": true,
     "S-Proposed-SM:m.b.c_TEXT-1_SI-1-body": true,
@@ -858,18 +856,16 @@ const knownFailures = {
     "D-Proposed-TR3rs:3-1_SO1-div": true,
     "D-Proposed-TR3rs:3-1_SO2-dM": true,
     "D-Proposed-TR3rs:3-1_SO2-body": true,
     "D-Proposed-TR3rs:3-1_SO2-div": true,
     "D-Proposed-TR3rs:3-1_SO3-dM": true,
     "D-Proposed-TR3rs:3-1_SO3-body": true,
     "D-Proposed-TR3rs:3-1_SO3-div": true,
     "D-Proposed-DIV:ce:false-1_SB-dM": true,
-    "D-Proposed-DIV:ce:false-1_SB-body": true,
-    "D-Proposed-DIV:ce:false-1_SB-div": true,
     "D-Proposed-DIV:ce:false-1_SL-dM": true,
     "D-Proposed-DIV:ce:false-1_SL-body": true,
     "D-Proposed-DIV:ce:false-1_SL-div": true,
     "D-Proposed-DIV:ce:false-1_SR-dM": true,
     "D-Proposed-DIV:ce:false-1_SR-body": true,
     "D-Proposed-DIV:ce:false-1_SR-div": true,
     "D-Proposed-DIV:ce:false-1_SI-dM": true,
     "D-Proposed-SPAN:d:ib-2_SL-dM": true,
@@ -1837,11 +1833,11 @@ const knownFailures = {
     "QV-Proposed-HC_SPANs:bc:b12-SPAN-1_SI-dM": true,
     "QV-Proposed-HC_SPANs:bc:b12-SPAN-1_SI-body": true,
     "QV-Proposed-HC_SPANs:bc:b12-SPAN-1_SI-div": true,
     "QV-Proposed-HC_SPAN.bcred-1_SI-dM": true,
     "QV-Proposed-HC_SPAN.bcred-1_SI-body": true,
     "QV-Proposed-HC_SPAN.bcred-1_SI-div": true,
     "QV-Proposed-HC_MYBCRED-1-SI-dM": true,
     "QV-Proposed-HC_MYBCRED-1-SI-body": true,
-    "QV-Proposed-HC_MYBCRED-1-SI-div": true
-  }
-}
+    "QV-Proposed-HC_MYBCRED-1-SI-div": true,
+  },
+};