https://bugs.webkit.org/show_bug.cgi?id=120780

Reviewed by Tim Horton.

When a repaint happened on a layer with a filter, and which paints into
its compositing ancestor, we'd repaint the wrong layer (and assert).

Fix by ensuring that RenderLayer::enclosingFilterLayer() takes paintsIntoCompositedAncestor()
into account, by adding a function that we share between three callers who
check isComposited() && !paintsIntoCompositedAncestor(). I didn't use a function
on RenderLayer, because I wanted it to be inline but to not #include RenderLayerBacking
in RenderLayer.h.

Test: compositing/filters/opacity-change-on-filtered-paints-into-ancestor.html

* dom/Node.cpp: Drive-by removal of #include "RenderLayer.h"
* rendering/RenderLayer.cpp:
(WebCore::compositedWithOwnBackingStore):
(WebCore::RenderLayer::enclosingCompositingLayerForRepaint):
(WebCore::RenderLayer::enclosingFilterRepaintLayer):
(WebCore::RenderLayer::clippingRootForPainting):

LayoutTests: Fix repaint issue on "paints into ancestor" filtered layers
https://bugs.webkit.org/show_bug.cgi?id=120780
<rdar://problem/14884148>

Reviewed by Tim Horton.

Ref test for opacity change on a filtered layer which paints into its compositing ancestor.

* compositing/filters/opacity-change-on-filtered-paints-into-ancestor-expected.html: Added.
* compositing/filters/opacity-change-on-filtered-paints-into-ancestor.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155131 268f45cc-cd09-0410-ab3c-d52691b4dbfc