[webkit-reviews] review requested: [Bug 120457] [CSS Regions] The layers from the flow thread should be collected under the regions' layers. : [Attachment 214691] patch that fixes the failing test

[bugzilla-daemon at webkit.org]

Mihai Maerean <mmaerean at adobe.com> has asked  for review:
Bug 120457: [CSS Regions] The layers from the flow thread should be collected
under the regions' layers.
https://bugs.webkit.org/show_bug.cgi?id=120457

Attachment 214691: patch that fixes the failing test
https://bugs.webkit.org/attachment.cgi?id=214691&action=review

------- Additional Comments from Mihai Maerean <mmaerean at adobe.com>
This patch has landed before (as http://trac.webkit.org/changeset/156451), but
was reverted because
fast/multicol/mixed-positioning-stacking-order.html failed. The fix is inside
RenderLayerCompositor::canBeComposited
that only enables compositing for layers inside flow threads that collect the
graphics layers under the regions.

Another change from changeset #156451 is that now the region renderers are
created as anonymous renderers under
the element that has the flow-from property. When a composited layer is needed
for the region, it sits in it's
parent renderer, not in the region renderer (RenderNamedFlowFragment).