Get rid of js-test-post-async.

This file doesn't serve any purpose. Getting rid of it gets
us one step closer to getting rid of js-test-post.

Review URL: https://codereview.chromium.org/51333009

git-svn-id: svn://svn.chromium.org/blink/trunk@160979 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add repaint-after-layout feature.

This adds the mechanisms to allow adding --enable-repaint-after-layout into
chrome. This will guard the implementation of change to painting after layout
instead of during.

BUG=310398

Review URL: https://codereview.chromium.org/52093006

git-svn-id: svn://svn.chromium.org/blink/trunk@160980 bbb929c8-8fbe-4397-9dbb-9b2b20218538