Remove RenderWidget::WebWidgetHandlesCompositorScheduling

WebKit::WebWidget isn't directly involved in compositor scheduling any more
(due to https://codereview.chromium.org/11575049/). Instead of checking that
bit and going to WebWidget, RenderWidget can either self-schedule or go directly
to the WebLayerTreeView.

BUG=156175


Review URL: https://chromiumcodereview.appspot.com/11796003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@178747 0039d316-1c4b-4281-b951-d872f2087c98
4 files changed