Roll external/skia 086a427b0..c432b0ca8 (6 commits)
https://skia.googlesource.com/skia.git/+log/086a427b0..c432b0ca8
2017-07-18 ethannicholas@google.com fixed use-after-free in sksl switch statements
2017-07-18 mtklein@chromium.org minor fixes to start_pipeline_lowp
2017-07-18 rmistry@google.com Do not move over webpage archives, they are needed for capturing SKPs
2017-07-18 csmartdalton@google.com Add two test bots for coverage counting path renderer
2017-07-18 bsalomon@google.com Revert "Improvements to GPU dither."
2017-07-18 bsalomon@google.com Improvements to GPU dither.
Test: Presubmit checks will test this change.
Change-Id: Idf6a5458fa60f16466fd6962531c9cf700b7b200