This assertion fires often, but it doesn't indicate any kind of noteworthy error.
_startTracking should either remove its assert if it wants to allow those that call it to call it regardless of if it's already tracking, or those that call _startTracking should only call it if _tracking is false.
Created attachment 236990 [details]
I think this is the cause of the assertion constantly firing.
Created attachment 236991 [details]
And this is another solution.
That assert is pretty annoying. I think _mouseEntered should check.
(In reply to comment #4)
> That assert is pretty annoying. I think _mouseEntered should check.
I agree. I'll submit a patch to do this.
Created attachment 237187 [details]
Created attachment 237188 [details]
Comment on attachment 237188 [details]
Clearing flags on attachment: 237188
Committed r172991: <http://trac.webkit.org/changeset/172991>
All reviewed patches have been landed. Closing bug.