Merge 109060 - RenderLayer ClipRect not accounting for transforms

Merge 109060 - RenderLayer ClipRect not accounting for transforms
https://bugs.webkit.org/show_bug.cgi?id=76486

Reviewed by Simon Fraser.

Source/WebCore:

Test: compositing/layer-creation/overlap-transformed-and-clipped.html

This patch changes calculateClipRects() so that the clipRect
offset is allowed to be converted across layers with
transforms. This is necessary because the RenderLayerCompositor
needs clipRects in document space, rather than with respect to
some local clipping layer.

* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::calculateClipRects):
* rendering/RenderObject.cpp:
(WebCore::RenderObject::localToContainerPoint):
(WebCore):
* rendering/RenderObject.h:
(RenderObject):

LayoutTests:

* compositing/layer-creation/overlap-transformed-and-clipped-expected.png: Added.
* compositing/layer-creation/overlap-transformed-and-clipped-expected.txt: Added.
* compositing/layer-creation/overlap-transformed-and-clipped.html: Added.


TBR=shawnsingh@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=109794