Roll external/skia 0bf59e459..48e240573 (24 commits)

https://skia.googlesource.com/skia.git/+log/0bf59e459..48e240573

2018-03-14 ethannicholas@google.com fixed SkSL SPIR-V vector comparisons
2018-03-14 herb@google.com Add accessor and less for raw glyph ID and WS
2018-03-14 csmartdalton@google.com Add incompleteShortIntPrecision to SkSL StandaloneShaderCaps
2018-03-14 kjlubick@google.com Scale the GPU when running perf on Pixel(2)
2018-03-14 benjaminwagner@google.com Revert "Update clang_win to yesterday's build (from Chromium)."
2018-03-14 egdaniel@google.com Revert "Improve handling of GrPixelConfig in GrBackendTex/RT ctors"
2018-03-14 benjaminwagner@google.com Revert "Add Win x86 Clang Perf/Test jobs."
2018-03-14 reed@google.com hide SkBlurMaskFilter and SkBlurQuality
2018-03-14 herb@google.com Experiment: relax 4 byte alignment for glyph images
2018-03-14 egdaniel@google.com Revert "Add back missing unique key checks when creating CachedBitmap/Image Proxies"
2018-03-14 benjaminwagner@google.com Revert "Switch Win Exceptions Build to Clang."
2018-03-14 benjaminwagner@google.com Remove Goma builds and support in gn_flavor.
2018-03-14 angle-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com Roll skia/third_party/externals/angle2/ fccebffe6..87db7c524 (4 commits)
2018-03-14 csmartdalton@google.com ccpr: Add an attenuation parameter to triangle corners
2018-03-14 csmartdalton@google.com Add a shader cap for incomplete short int precision
2018-03-14 skcms-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com Roll skia/third_party/externals/skcms/ 6cecdee60..2b5c77024 (1 commit)
2018-03-14 kjlubick@google.com Cleanup TODO in gen_tasks
2018-03-14 benjaminwagner@google.com Switch Win Exceptions Build to Clang.
2018-03-14 benjaminwagner@google.com Add Win x86 Clang Perf/Test jobs.
2018-03-14 robertphillips@google.com Provide promise images when rendering SKPs w/ DDL
2018-03-14 bsalomon@google.com Ensure that GrGpu state tracking is initialized before making a backend RT/Tex in tests
2018-03-14 reed@google.com add explicit API to know if the writebuffer is using its external storage
2018-03-14 egdaniel@google.com Improve handling of GrPixelConfig in GrBackendTex/RT ctors
2018-03-14 egdaniel@google.com Add back missing unique key checks when creating CachedBitmap/Image Proxies

The AutoRoll server is located here: https://android-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
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Test: Presubmit checks will test this change.
Change-Id: I0d763c42e3a6e126acc96d4be88525dd8346a015
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.