Oilpan: Change LoadableTextTrack::m_trackElement a strong Member

Source/core/html/track/LoadableTextTrack.h

Index: Source/core/html/track/LoadableTextTrack.h
diff --git a/Source/core/html/track/LoadableTextTrack.h b/Source/core/html/track/LoadableTextTrack.h
index 527290c0eb713fcfc2eb9dc7c4f857174e63dd03..fe86863e1ac5458b295c30900af6f33563a58ae3 100644
--- a/Source/core/html/track/LoadableTextTrack.h
+++ b/Source/core/html/track/LoadableTextTrack.h
@@ -70,9 +70,7 @@ private:
 
     void loadTimerFired(Timer<LoadableTextTrack>*);
 
-    // FIXME: Oilpan: This should be a strong pointer once Member pointers
-    // into the Node hierarchy can be used.
-    RawPtrWillBeWeakMember<HTMLTrackElement> m_trackElement;
+    RawPtrWillBeMember<HTMLTrackElement> m_trackElement;
     Timer<LoadableTextTrack> m_loadTimer;
     OwnPtrWillBeMember<TextTrackLoader> m_loader;
     KURL m_url;