Support Mac platform-specific image controls This is an umbrella bug.
<rdar://problem/15964809>
Working on cross platform infrastructure to WebCore for now, as started in 129022, 129027, and a few more to come. Then we'll be piping things up through to WebKit and adding more behavior there.
Bug https://bugs.webkit.org/show_bug.cgi?id=129080 lays the groundwork with an Image Controls shadow dom, rendering on top of an image.