Remove RenderWidget incremental compositing update.

This code was added in http://src.chromium.org/viewvc/blink?view=revision&revision=62894.
As per the change description, it was needed because
updateGraphicsLayerGeometry was called in the middle of layout.
We now only call updateGraphicsLayerGeometry from the
compositing update phase, so we don't need this code anymore.

BUG=343756

Review URL: https://codereview.chromium.org/247833002

git-svn-id: svn://svn.chromium.org/blink/trunk@172282 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Change run-webkit-tests to return a fixed error code when bailing out early.

Previously we would return the number of tests that actually failed. The
blink_trybot recipe could not distinguish that case from the case where
we ran to completion but had that many errors. Really we shouldn't be
returning the number of tests that fail at all -- crbug.com/357866 --
but I need to do some more testing and investigating to see if anything
else breaks if I remove that. In the mean time, we introduce a new
dedicated error code to indicate that we bailed out early and the
try job should be aborted.

R=eseidel@chromium.org
BUG=365717

Review URL: https://codereview.chromium.org/246403005

git-svn-id: svn://svn.chromium.org/blink/trunk@172283 bbb929c8-8fbe-4397-9dbb-9b2b20218538