Roll src/third_party/skia/ 828930677..f12d84275 (7 commits)

https://skia.googlesource.com/skia.git/+log/828930677138..f12d84275cfa

$ git log 828930677..f12d84275 --date=short --no-merges --format='%ad %ae %s'
2017-08-02 skia-deps-roller Roll skia/third_party/externals/angle2/ 8f276e255..6c58b0620 (2 commits)
2017-08-02 liyuqian Fix typo XPS to SVG
2017-08-02 stani Add a private API for writing the clip to the stencil
2017-08-02 ethannicholas Revert "Revert "support for 'half' types in sksl, plus general numeric type improvements""
2017-08-02 robertphillips Fix DeferredTextureImage test on Mac
2017-08-02 skia-deps-roller Roll skia/third_party/externals/angle2/ df7d7c9ec..8f276e255 (1 commit)
2017-08-02 brianosman Guard against D3D NaN/Infinity literals bug in color burn

Created with:
  roll-dep src/third_party/skia


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

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls


CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=liyuqian@chromium.org

Change-Id: I5b7df679f3a83d0e26a9352f2b763497276cbc1e
Reviewed-on: https://chromium-review.googlesource.com/599348Reviewed-by: Skia Deps Roller <skia-deps-roller@chromium.org>
Commit-Queue: Skia Deps Roller <skia-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491606}

DEPS

@@ -40,7 +40,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': '8289306771381298cf3b87183882cc1f1fef4dc3',
+  'skia_revision': 'f12d84275cfaff4b140694e33313a3581955abf8',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.