Bug 1664741 - Make `AutoBlockElementsJoiner::DeleteNodesEntirelyInRangeButKeepTableStructure()` check whether it deletes a visible content or not before deleting the contents r=m_kato

Oddly, it checks whether it deletes at least one visible thing after deleting
each content from the DOM tree.  It should be done before deleting from the
DOM tree because all text nodes become visible if they are not in the DOM tree
anymore.

Unfortunately, this change does not fix any automated test result, but the
base logic --only when it does not delete any visible things, join the adjacent
block elements-- sounds reasonable.  Therefore, let's take this change.
Note that without this change, cannot compute "affected ranges" of
`getTargetRanges()` in the case running this method later.

Differential Revision: https://phabricator.services.mozilla.com/D90065

editor/libeditor/HTMLEditSubActionHandler.cpp

@@ -3028,6 +3028,11 @@ class MOZ_STACK_CLASS HTMLEditor::AutoDeleteRangesHandler final {
     DeleteNodesEntirelyInRangeButKeepTableStructure(
         HTMLEditor& aHTMLEditor, nsRange& aRange,
         AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed);
+    bool NeedsToJoinNodesAfterDeleteNodesEntirelyInRangeButKeepTableStructure(
+        const HTMLEditor& aHTMLEditor,
+        const nsTArray<OwningNonNull<nsIContent>>& aArrayOfContents,
+        AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed)
+        const;
 
     /**
      * DeleteContentButKeepTableStructure() removes aContent if it's an element
@@ -5258,7 +5263,9 @@ Result<bool, nsresult> HTMLEditor::AutoDeleteRangesHandler::
   iter.AppendAllNodesToArray(arrayOfTopChildren);
 
   // Now that we have the list, delete non-table elements
-  bool join = true;
+  bool needsToJoinLater =
+      NeedsToJoinNodesAfterDeleteNodesEntirelyInRangeButKeepTableStructure(
+          aHTMLEditor, arrayOfTopChildren, aSelectionWasCollapsed);
   for (auto& content : arrayOfTopChildren) {
     // XXX After here, the child contents in the array may have been moved
     //     to somewhere or removed.  We should handle it.
@@ -5279,26 +5286,46 @@ Result<bool, nsresult> HTMLEditor::AutoDeleteRangesHandler::
         NS_SUCCEEDED(rv),
         "AutoBlockElementsJoiner::DeleteContentButKeepTableStructure() failed, "
         "but ignored");
-    // If something visible is deleted, no need to join.  Visible means
-    // all nodes except non-visible textnodes and breaks.
-    // XXX Odd.  Why do we check the visibility after removing the node
-    //     from the DOM tree?
-    if (!join || aSelectionWasCollapsed ==
-                     AutoDeleteRangesHandler::SelectionWasCollapsed::No) {
-      continue;
-    }
+  }
+  return needsToJoinLater;
+}
+
+bool HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::
+    NeedsToJoinNodesAfterDeleteNodesEntirelyInRangeButKeepTableStructure(
+        const HTMLEditor& aHTMLEditor,
+        const nsTArray<OwningNonNull<nsIContent>>& aArrayOfContents,
+        AutoDeleteRangesHandler::SelectionWasCollapsed aSelectionWasCollapsed)
+        const {
+  // If original selection was collapsed, we need always to join the nodes.
+  // XXX Why?
+  if (aSelectionWasCollapsed ==
+      AutoDeleteRangesHandler::SelectionWasCollapsed::No) {
+    return true;
+  }
+  // If something visible is deleted, no need to join.  Visible means
+  // all nodes except non-visible textnodes and breaks.
+  if (aArrayOfContents.IsEmpty()) {
+    return true;
+  }
+  for (const OwningNonNull<nsIContent>& content : aArrayOfContents) {
     if (content->IsText()) {
-      join = !aHTMLEditor.IsInVisibleTextFrames(*content->AsText());
+      if (aHTMLEditor.IsInVisibleTextFrames(*content->AsText())) {
+        return false;
+      }
       continue;
     }
+    // XXX If it's an element node, we should check whether it has visible
+    //     frames or not.
     if (!content->IsElement() ||
         aHTMLEditor.IsEmptyNode(*content->AsElement())) {
       continue;
     }
-    join = content->IsHTMLElement(nsGkAtoms::br) &&
-           !aHTMLEditor.IsVisibleBRElement(content);
+    if (!content->IsHTMLElement(nsGkAtoms::br) ||
+        aHTMLEditor.IsVisibleBRElement(content)) {
+      return false;
+    }
   }
-  return join;
+  return true;
 }
 
 nsresult HTMLEditor::AutoDeleteRangesHandler::AutoBlockElementsJoiner::