Update layout test expectation

Remove fast/dom/shadow/transition-on-shadow-host-with-ditributed-node.html
as this no longer time outs.

BUG=318431
TEST=fast/dom/shadow/transition-on-shadow-host-with-distributed-node.html does not time out

Review URL: https://codereview.chromium.org/444383002

git-svn-id: svn://svn.chromium.org/blink/trunk@179804 bbb929c8-8fbe-4397-9dbb-9b2b20218538