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

Source/core/html/track/CueTimeline.h

Index: Source/core/html/track/CueTimeline.h
diff --git a/Source/core/html/track/CueTimeline.h b/Source/core/html/track/CueTimeline.h
index 5a11af42a8a0068708b9f527dceda613e54e8eb6..8bd32208e1d4e7274b0432194fe3a68905e10e23 100644
--- a/Source/core/html/track/CueTimeline.h
+++ b/Source/core/html/track/CueTimeline.h
@@ -28,7 +28,8 @@ typedef Vector<CueInterval> CueList;
 
 // This class manages the timeline and rendering updates of cues associated
 // with TextTracks. Owned by a HTMLMediaElement.
-class CueTimeline : public NoBaseWillBeGarbageCollectedFinalized<CueTimeline> {
+class CueTimeline final : public NoBaseWillBeGarbageCollectedFinalized<CueTimeline> {
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(CueTimeline);
 public:
     CueTimeline(HTMLMediaElement&);