Merge 104782 - Repaint all graphics layers when their renderer offset changes

Merge 104782 - Repaint all graphics layers when their renderer offset changes
https://bugs.webkit.org/show_bug.cgi?id=75730

Reviewed by Simon Fraser.

Source/WebCore:

In RenderLayerBacking, only the main graphics layer gets repainted
when the offset changes. If the offset on other graphics layers (e.g.
the foreground layer) changes, they should get repainted as well.

Test: compositing/geometry/foreground-offset-change.html

* platform/graphics/GraphicsLayer.cpp:
(WebCore::GraphicsLayer::setOffsetFromRenderer):
(WebCore::GraphicsLayer::paintGraphicsLayerContents):
* platform/graphics/GraphicsLayer.h:
* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::updateGraphicsLayerGeometry):
(WebCore::RenderLayerBacking::paintContents):

LayoutTests:

* compositing/geometry/foreground-offset-change-expected.png: Added.
* compositing/geometry/foreground-offset-change-expected.txt: Added.
* compositing/geometry/foreground-offset-change.html: Added.


TBR=enne@google.com
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=104854