This is a regression caused by https://bugs.webkit.org/show_bug.cgi?id=109426 which broke the layout for nested SplitView instances of different orientations. This breaks Canvas profiler in particular.
Created attachment 188354 [details]
Comment on attachment 188354 [details]
Clearing flags on attachment: 188354
Committed r142878: <http://trac.webkit.org/changeset/142878>
All reviewed patches have been landed. Closing bug.