[chromium] Avoid culling work for fully-non-opaque tiles, and add tracing for draw...

[chromium] Avoid culling work for fully-non-opaque tiles, and add tracing for draw culling
https://bugs.webkit.org/show_bug.cgi?id=79183

Patch by Dana Jansens <danakj@chromium.org> on 2012-02-24
Reviewed by James Robinson.

Addresses performance issues with draw culling by avoiding the work
of mapRect and other function calls when the quad has no opaque area.
And adds a TRACE_EVENT to watch the time spent in draw culling.

* platform/graphics/chromium/cc/CCLayerTreeHostImpl.cpp:
(WebCore::CCLayerTreeHostImpl::optimizeRenderPasses):
* platform/graphics/chromium/cc/CCQuadCuller.cpp:
(WebCore::CCQuadCuller::cullOccludedQuads):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108764 268f45cc-cd09-0410-ab3c-d52691b4dbfc