Fix GPU clipped-AA vs. non-AA drawRect discrepancy

In the clip stack we were manually rounding out non-AA clip rects but leaving the hardening of non-AA drawRects up to the GPU. In some border cases the GPU can truncate rather than round out resulting in visual discrepancies.

BUG=423834

Review URL: https://codereview.chromium.org/839883003
4 files changed