[chromium] Switch to new webkit_support::CreateLayerTreeView interface
https://bugs.webkit.org/show_bug.cgi?id=111285

Patch by James Robinson <jamesr@chromium.org> on 2013-03-04
Reviewed by Adrienne Walker.

This removes the need for WebCompositorSupport::initialize and exposes
slightly fewer entry points across the repository boundary.

* DumpRenderTree/chromium/TestShell.cpp:
(TestShell::initialize):
* DumpRenderTree/chromium/TestShell.h:
(TestShell::webCompositorThread):
(TestShell):
* DumpRenderTree/chromium/WebViewHost.cpp:
(WebViewHost::initializeLayerTreeView):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144705 268f45cc-cd09-0410-ab3c-d52691b4dbfc