Safari creates a blank web page when it is opened. This page will not be visible unless the user selects to open new tabs with "Empty page". The loader of this page forces Document::resolveStyle() which requires RenderLayerCompositor::scheduleLayerFlushNow().
Before r244182, this would just call scheduleCompositingLayerFlush() immediately. After r244182, RenderLayerCompositor::scheduleLayerFlushNow() has to schedule a RenderingUpdate and when it fires it calls scheduleCompositingLayerFlush().
We need to optimize this case by checking whether the page is visible or not before scheduling the RenderingUpdate.
Created attachment 368642 [details]
Created attachment 368684 [details]
Comment on attachment 368684 [details]
Clearing flags on attachment: 368684
Committed r244837: <https://trac.webkit.org/changeset/244837>
All reviewed patches have been landed. Closing bug.