Turn clear-to-white-then-intersect clips into clear-to-black-then-replace

R=robertphillips@google.com, brian@thesalomons.net

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/27170003

git-svn-id: http://skia.googlecode.com/svn/trunk@11786 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed