Remove scheduleLayerUpdate from RenderLayerCompositor.

Now that frames always have a layer and get their self-painting
bit updated whenever m_compositing changes, we don't need to
do a layer update when they get composited. Instead we just
need to mark the frame in the owner page as needing a compositing
update.

This removes one of the needs for applyUpdateLayerCompositingStateChickenEggHacks.

BUG=379097

Review URL: https://codereview.chromium.org/302093002

git-svn-id: svn://svn.chromium.org/blink/trunk@175505 bbb929c8-8fbe-4397-9dbb-9b2b20218538