Bug 815666 - Add a helper class to coalesce frames that need their overflow updated. r=roc a=akeybl
Bug 815666 - Use OverflowUpdateTracker to avoid calling UpdateOverflow on the same frame multiple times. r=roc a=akeybl
Bug 822906 - Add SplayTree to mfbt. r=waldo a=akeybl
Bug 822906 - Use SplayTree to remove deleted frames from RestyleTracker. r=roc a=akeybl