If you open a page with a composited layer taller than the current window and scroll, the layer will be clipped.
Created attachment 46720 [details]
Attachment 46720 [details] did not pass style-queue:
Failed to run "WebKitTools/Scripts/check-webkit-style" exit_code: 1
WebCore/platform/graphics/win/WKCACFLayerRenderer.cpp:231: Should have a space between // and comment [whitespace/comments] 
WebCore/platform/graphics/win/WKCACFLayerRenderer.cpp:232: Should have a space between // and comment [whitespace/comments] 
Total errors found: 2
Comment on attachment 46720 [details]
> + //m_rootLayer->setAnchorPoint(CGPointMake(0, 1));
> + //CGPoint pos = m_rootLayer->position();
You should remove this commented-out code. Unless it's needed.
While I'm not as familiar with this code as some, and there's no regression testing here, the patch looks fine otherwise. Please remove the commented-out code.
And if you think someone else (Simon) should review this, feel free to change back from review+ to review?.
Got rid of comments as per Darin's comment.
Landed in http://trac.webkit.org/changeset/53415