Output repaint rects for svg repaint tests

Previously all of these tests were converted to not output repaint rects
and just output pixels.  This ended up being a loss of information that
was useful to detecting missing repaints, and so they should be turned
back on where it makes sense.

BUG=369609

Review URL: https://codereview.chromium.org/262963003

git-svn-id: svn://svn.chromium.org/blink/trunk@173666 bbb929c8-8fbe-4397-9dbb-9b2b20218538