Full invalidate <img> on resize

Because <img> scale its contents on resize, incremental invalidation
doesn't apply to it. Force full invalidate if the image content is
resized during layout.

BUG=397939
TEST=fast/repaint/image-resize.html
TEST=fast/repaint/percent-size-image-resize-container.html

Review URL: https://codereview.chromium.org/458373003

git-svn-id: svn://svn.chromium.org/blink/trunk@180015 bbb929c8-8fbe-4397-9dbb-9b2b20218538