Should not use clipOutRoundedRect when a given rounded rect is empty.

BUG=303922,303383
TEST=fast/borders/border-radius-with-empty-inner-border.html,fast/borders/empty-border-radius.html

Review URL: https://codereview.chromium.org/25977004

git-svn-id: svn://svn.chromium.org/blink/trunk@159641 bbb929c8-8fbe-4397-9dbb-9b2b20218538
8 files changed