Fix failures in webkit_unit_tests and re-enable CCLayerTreeHostTestSetSingleLostContext.runMultiThread.
Created attachment 134084 [details] Patch
These problems occur because the request for filter contexts is left open, and subsequent tests actually attempt to allocate a real GL context, which asserts because SetGLImplementation() hasn't been called. For now, I'm just cancelling the request for filter contexts after the occlusion tests run. A longer-term solution might be to mock out the GL context (either as the compositor context is mocked in the Web.*Client, or by calling SetGLImplementation(kGLImplementationMockGL), but since this is all probably going to change once we can create contexts in the impl thread, this will keep things running for now.
Comment on attachment 134084 [details] Patch Seems reasonable
Committed r112278: <http://trac.webkit.org/changeset/112278>