Comments on a region of an image or document have review comment
thumbnails containing an image element of that region. If the original
image or document is quite high definition, the image can be wider than
the review container, leading to horizontal overflow.

A nicer viewing experience is capping the image width to the size of the
container, so that the full image is in view. This change achieves that.

Viewed an image region comment that was previously overflowed, looks

  nicer now.
Viewed image region comments that are not overflown, they still look

  normal.