compositing/layer-creation/overlap-transformed-preserved-3d.html fails on Linux Debug

TBR=wangxianzhu@chromium.org
BUG=387398

Review URL: https://codereview.chromium.org/350543004

git-svn-id: svn://svn.chromium.org/blink/trunk@176701 bbb929c8-8fbe-4397-9dbb-9b2b20218538