The condition for the timeout handler in AcceleratedCompositingContext::renderLayersToWindow() doesn't seem to be ok.
I added parentheses in r151198 to make the precedence rules explicit but after double checking with Martin it turns out that it was already wrong and needed to be changed instead.
Created attachment 203856 [details]
Comment on attachment 203856 [details]
Clearing flags on attachment: 203856
Committed r151245: <http://trac.webkit.org/changeset/151245>
All reviewed patches have been landed. Closing bug.