Fixing src rectangle clipping with drawImage

BUG=260292
TEST=LayoutTests/fast/canvas/canvas-drawImage-out-of-bounds-src.html

Review URL: https://chromiumcodereview.appspot.com/19267027

git-svn-id: svn://svn.chromium.org/blink/trunk@154798 bbb929c8-8fbe-4397-9dbb-9b2b20218538