This CL put [Exposed=(Window,Worker)] in the ImageBitmap.idl

Along with that, some of the layout tests results has to be updated.

Also, a layout test has been updated to show that the worker is
able to get width&height for an ImageBitmap.

The thread of Intent to ship ImageBitmap can be found here:
https://groups.google.com/a/chromium.org/d/topic/blink-dev/jRzvehX9U1U/discussion

BUG=563984

Review URL: https://codereview.chromium.org/1486663002

Cr-Commit-Position: refs/heads/master@{#370179}
9 files changed