Removed Pass/Fail expectations for canvas-ImageData-behaviour

The V8 roll that changed this behavior is now in Chromium, so these tests
should pass again.

BUG=424756
TBR=dslomov@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/660843006

git-svn-id: svn://svn.chromium.org/blink/trunk@184017 bbb929c8-8fbe-4397-9dbb-9b2b20218538