Disentangle updating the ScrollingCoordinator from RenderLayerCompositor

We only need to update the ScrollingCoordinator once at the root of the frame
tree. We shouldn't be poking at it at every level of the recursion.

This CL finally achieves my dream of controlling
RenderLayerCompositor::updateIfNeeded with just the CompositingUpdateType enum.

Review URL: https://codereview.chromium.org/330513002

git-svn-id: svn://svn.chromium.org/blink/trunk@176046 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Descend into inner blocks for inflateAutoTable.

BUG=371611

Review URL: https://codereview.chromium.org/320393003

git-svn-id: svn://svn.chromium.org/blink/trunk@176047 bbb929c8-8fbe-4397-9dbb-9b2b20218538