GitLab

- All files from webkit/renderer/compositor_bindings have been moved to content/renderer/compositor_bindings
- Webkit_compositor_support is moved in content_renderer
- Webkit_compositor_bindings_unittests is moved in content_unittests
- A dummy target has been left for webkit_compositor_bindings_unittests so as to not break the build.

TBR=nduca

BUG=265753

Review URL: https://codereview.chromium.org/317163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@277988 0039d316-1c4b-4281-b951-d872f2087c98