Make sure the Frame always gets destroyed on the main thread.
Since http://trac.webkit.org/changeset/181791, Frame is ThreadSafeRefCounted and captured on other threads. We should make sure the Frame is always destroyed on the main thread though, since it is a main thread object and we hold WeakPtrs to it in many places.
Created attachment 425220 [details]
Committed r275475: <https://commits.webkit.org/r275475>
All reviewed patches have been landed. Closing bug and clearing flags on attachment 425220 [details].