Make classes and structures in core/editing fast-allocated.

Source/core/editing/Editor.h

Index: Source/core/editing/Editor.h
diff --git a/Source/core/editing/Editor.h b/Source/core/editing/Editor.h
index 984d3486d992e58056cd40634431c77932344828..e69107355a2ab122562651c377203f2d92261379 100644
--- a/Source/core/editing/Editor.h
+++ b/Source/core/editing/Editor.h
@@ -60,6 +60,7 @@ enum EditorCommandSource { CommandFromMenuOrKeyBinding, CommandFromDOM };
 enum EditorParagraphSeparator { EditorParagraphSeparatorIsDiv, EditorParagraphSeparatorIsP };
 
 class CORE_EXPORT Editor final : public NoBaseWillBeGarbageCollectedFinalized<Editor> {
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(Editor);
     WTF_MAKE_NONCOPYABLE(Editor);
 public:
     static PassOwnPtrWillBeRawPtr<Editor> create(LocalFrame&);