Roll external/skia 5a66efbba..baf3e7809 (7 commits)

https://skia.googlesource.com/skia.git/+log/5a66efbba..baf3e7809

2018-03-08 csmartdalton@google.com Revert "ccpr: Draw curves in a single pass"
2018-03-08 csmartdalton@google.com Revert "ccpr: Simplify triangle corners"
2018-03-08 fmalita@chromium.org Use kLow_SkFilterQuality when generating shader masks
2018-03-08 egdaniel@google.com Add testing only helper to flush and sync gpu.
2018-03-08 bsalomon@google.com Delazify wrapped backend textures/render target proxies
2018-03-08 robertphillips@google.com Additional DDL playback cleanup
2018-03-08 angle-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com Roll skia/third_party/externals/angle2/ ed8b49195..5164b797c (1 commit)

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Change-Id: I3ecb783171bf719924603bd1c959d8fddc2dea75
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