Drawing an animated image to a canvas now behave as expected

According to the spec, drawing an animated image to a canvas should only
draw the first frame.

BUG=286673

Review URL: https://codereview.chromium.org/388253004

git-svn-id: svn://svn.chromium.org/blink/trunk@178959 bbb929c8-8fbe-4397-9dbb-9b2b20218538