Revert "Revert "speed up A8 by creating a new entry-point in SkDraw that blits the path's coverage directly into an A8 target, regardless of the previous pixel values.""

This reverts commit 3c77887b3eb2d32ab668ab4e5f2f9e79103956e8.

BUG=

Review URL: https://codereview.chromium.org/50673005

git-svn-id: http://skia.googlecode.com/svn/trunk@12167 2bbb7eff-a529-9590-31e7-b0007b416f81
10 files changed