Revert blink r162392

This patch accidentally regressed layer sorting and may have possibly
been a cause of some crashes on tip of tree.

BUG=322232, 322628
TBR=vollick@chromium.org

Review URL: https://codereview.chromium.org/83123007

git-svn-id: svn://svn.chromium.org/blink/trunk@162567 bbb929c8-8fbe-4397-9dbb-9b2b20218538