[chromium] Clear RenderSurfaces still when no idle paint will be done

[chromium] Clear RenderSurfaces still when no idle paint will be done
https://bugs.webkit.org/show_bug.cgi?id=90553

Reviewed by Adrienne Walker.

Source/WebCore:

Currently if idle painting is disabled, updateLayers() will early-out.
But this prevents it from doing cleanup and clearing all RenderSurface
pointers, leaving the layer tree in an unexpected state.

Tests: CCLayerTreeHostTestCompositeAndReadbackCleanup

* platform/graphics/chromium/cc/CCLayerTreeHost.cpp:
(WebCore::CCLayerTreeHost::updateLayers):

Source/WebKit/chromium:

* tests/CCLayerTreeHostTest.cpp:
(CCLayerTreeHostTestCompositeAndReadbackCleanup):
(WTF::CCLayerTreeHostTestCompositeAndReadbackCleanup::CCLayerTreeHostTestCompositeAndReadbackCleanup):
(WTF::CCLayerTreeHostTestCompositeAndReadbackCleanup::beginTest):
(WTF::CCLayerTreeHostTestCompositeAndReadbackCleanup::afterTest):
(WTF):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121864 268f45cc-cd09-0410-ab3c-d52691b4dbfc