Roll external/skia a50deea95..4ba4b10ea (11 commits)

https://skia.googlesource.com/skia.git/+log/a50deea95..4ba4b10ea

2017-10-30 angle-deps-roller@chromium.org Roll skia/third_party/externals/angle2/ e7c5f4f05..163965d5c (1 commit)
2017-10-30 egdaniel@google.com Have mip status match surface when snapping image from wrapped object
2017-10-30 mtklein@chromium.org make color rotating a little less pointlessly slow
2017-10-30 egdaniel@google.com Add mip support to GrAHardwareBufferImageGenerator
2017-10-30 angle-deps-roller@chromium.org Roll skia/third_party/externals/angle2/ 55bc905f0..e7c5f4f05 (2 commits)
2017-10-30 robertphillips@google.com Revert "Revert "Fix Debian9-Clang build""
2017-10-30 robertphillips@google.com Revert "Revert "Fix GrDefaultPathRender inversely wound path bug""
2017-10-30 robertphillips@google.com Suppress Gr*PathRendererTests on Vulkan NexusPlayer and Iris 540
2017-10-30 angle-deps-roller@chromium.org Roll skia/third_party/externals/angle2/ 87c358839..55bc905f0 (1 commit)
2017-10-30 liyuqian@google.com Initialize mask to 0 during AntiRect optimization
2017-10-30 ethannicholas@google.com fix skslc splitting escape sequences in half

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Change-Id: Id56fd1ec1a7105f3cbccadaa208d076b211ef792
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