Bug 1990586 - Make WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt track given caret point a=pascalc

It's used as the result in some cases.  However, it's not tracked in
some cases when touching the DOM.

This modifies the API of `AutoTrackDOMPoint` to flush the tracking point
but can keep tracking.  We should use the new API in every place later.

(This manually merges `WhiteSpaceVisibilityKeeper.cpp` because ESR140
still has the pref to take the legacy mode back and that blocks applying
the patch cleanly.)

Differential Revision: https://phabricator.services.mozilla.com/D270643

editor/libeditor/EditorForwards.h

@@ -46,6 +46,7 @@ enum class EditorCommandParamType : uint16_t;  // mozilla/EditorCommands.h
 enum class EditSubAction : int32_t;            // mozilla/EditAction.h
 enum class ParagraphSeparator;                 // mozilla/HTMLEditor.h
 enum class SpecifiedStyle : uint8_t;           // mozilla/PendingStyles.h
+enum class StopTracking : bool;                // mozilla/SelectionState.h
 enum class SuggestCaret;                       // EditorUtils.h
 enum class WithTransaction;                    // HTMLEditHelpers.h
 

editor/libeditor/SelectionState.h

@@ -284,6 +284,8 @@ class MOZ_STACK_CLASS RangeUpdater final {
   bool mLocked;
 };
 
+enum class StopTracking : bool { No, Yes };
+
 /**
  * Helper class for using SelectionState.  Stack based class for doing
  * preservation of dom points across editor actions.
@@ -331,11 +333,13 @@ class MOZ_STACK_CLASS AutoTrackDOMPoint final {
 
   ~AutoTrackDOMPoint() { FlushAndStopTracking(); }
 
-  void FlushAndStopTracking() {
+  void Flush(StopTracking aStopTracking) {
     if (!mIsTracking) {
       return;
     }
-    mIsTracking = false;
+    if (static_cast<bool>(aStopTracking)) {
+      mIsTracking = false;
+    }
     if (mPoint.isSome()) {
       mRangeUpdater.DropRangeItem(mRangeItem);
       // Setting `mPoint` with invalid DOM point causes hitting `NS_ASSERTION()`
@@ -378,6 +382,8 @@ class MOZ_STACK_CLASS AutoTrackDOMPoint final {
     }
   }
 
+  void FlushAndStopTracking() { Flush(StopTracking::Yes); }
+
   void StopTracking() { mIsTracking = false; }
 
  private:

editor/libeditor/WhiteSpaceVisibilityKeeper.cpp

@@ -3450,6 +3450,11 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
     MOZ_ASSERT(
         StaticPrefs::editor_white_space_normalization_blink_compatible());
 
+    Maybe<AutoTrackDOMPoint> trackPointToPutCaret;
+    if (aCaretPoint.IsSet()) {
+      trackPointToPutCaret.emplace(aHTMLEditor.RangeUpdaterRef(),
+                                   &pointToPutCaret);
+    }
     // If we're removing a block, it may be surrounded by invisible
     // white-spaces.  We should remove them to avoid to make them accidentally
     // visible.
@@ -3459,8 +3464,6 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
       AutoTrackDOMPoint trackAtContent(aHTMLEditor.RangeUpdaterRef(),
                                        &atContent);
       {
-        AutoTrackDOMPoint trackPointToPutCaret(aHTMLEditor.RangeUpdaterRef(),
-                                               &pointToPutCaret);
         nsresult rv =
             WhiteSpaceVisibilityKeeper::EnsureNoInvisibleWhiteSpacesBefore(
                 aHTMLEditor, EditorDOMPoint(aContentToDelete.AsElement()));
@@ -3484,6 +3487,9 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
         if (NS_WARN_IF(!aContentToDelete.IsInComposedDoc())) {
           return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
         }
+        if (trackPointToPutCaret.isSome()) {
+          trackPointToPutCaret->Flush(StopTracking::No);
+        }
       }
       if (pointToPutCaret.IsInContentNode()) {
         // Additionally, we may put caret into the preceding block (this is the
@@ -3558,7 +3564,7 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
           }
         }
       }
-      trackAtContent.FlushAndStopTracking();
+      trackAtContent.Flush(StopTracking::Yes);
       if (NS_WARN_IF(!atContent.IsInContentNodeAndValidInComposedDoc())) {
         return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
       }
@@ -3584,7 +3590,7 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
               "failed");
           return afterLastVisibleThingOrError.propagateErr();
         }
-        trackAtContent.FlushAndStopTracking();
+        trackAtContent.Flush(StopTracking::Yes);
         if (NS_WARN_IF(!atContent.IsInContentNodeAndValidInComposedDoc())) {
           return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
         }
@@ -3604,7 +3610,7 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
             "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesBefore() failed");
         return atFirstVisibleThingOrError.propagateErr();
       }
-      trackAtContent.FlushAndStopTracking();
+      trackAtContent.Flush(StopTracking::Yes);
       if (NS_WARN_IF(!atContent.IsInContentNodeAndValidInComposedDoc())) {
         return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
       }
@@ -3616,13 +3622,22 @@ WhiteSpaceVisibilityKeeper::DeleteContentNodeAndJoinTextNodesAroundIt(
           aContentToDelete, {WalkTreeOption::IgnoreNonEditableNode});
   // Delete the node, and join like nodes if appropriate
   {
-    AutoTrackDOMPoint trackPointToPutCaret(aHTMLEditor.RangeUpdaterRef(),
+    Maybe<AutoTrackDOMPoint> trackPointToPutCaret;
-                                           &pointToPutCaret);
+    if (pointToPutCaret.IsSet()) {
+      trackPointToPutCaret.emplace(aHTMLEditor.RangeUpdaterRef(),
+                                   &pointToPutCaret);
+    }
     nsresult rv = aHTMLEditor.DeleteNodeWithTransaction(aContentToDelete);
     if (NS_FAILED(rv)) {
       NS_WARNING("EditorBase::DeleteNodeWithTransaction() failed");
       return Err(rv);
     }
+    if (trackPointToPutCaret.isSome()) {
+      trackPointToPutCaret->Flush(StopTracking::Yes);
+      if (NS_WARN_IF(!pointToPutCaret.IsInContentNode())) {
+        return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
+      }
+    }
   }
 
   // Are they both text nodes?  If so, join them!

testing/web-platform/tests/editing/crashtests/delete-in-empty-editable-document-element.html

@@ -0,0 +1,17 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script>
+"use strict";
+
+addEventListener("DOMContentLoaded", () => {
+  document.documentElement.contentEditable = "plaintext-only";
+  document.execCommand("delete");
+}, {once: true});
+</script>
+</head>
+<body>
+<track></track>
+</body>
+</html>