SkiaRenderer's handling of AA edges is slightly different (up to 10
difference in the RGB values), but perceptually close enough. Add images
specific to SkiaRenderer to the tests AntiAliasing and
AntiAliasingPerspective.

Bug: 947055
Change-Id: If7e9571ec6a038d28786b23e21870ea5a4312146
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1553879Reviewed-by: Jonathan Backer <backer@chromium.org>
Commit-Queue: Sean Gilhuly <sgilhuly@chromium.org>
Cr-Commit-Position: refs/heads/master@{#648744}