Roll src/third_party/skia/ 7ffbcf909..60b1b6e76 (6 commits)

https://skia.googlesource.com/skia.git/+log/7ffbcf909d36..60b1b6e76e98

$ git log 7ffbcf909..60b1b6e76 --date=short --no-merges --format='%ad %ae %s'
2017-12-04 angle-deps-roller Roll skia/third_party/externals/angle2/ d5f44c986..f5be5bafa (1 commit)
2017-12-04 reed helper api to force a raster image
2017-12-04 csmartdalton turn on extended Clang warnings on Windows too
2017-12-04 mtklein Only look at gamut_transform if we wrote to it.
2017-12-04 robertphillips Add resource cache limits to SkSurfaceCharacterization
2017-12-04 benjaminwagner Fix recipe comments for ASAN.

Created with:
  roll-dep src/third_party/skia


The AutoRoll server is located here: https://autoroll.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
be CC'd on the roll, and stop the roller if necessary.


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
TBR=rmistry@chromium.org

Change-Id: Id5869fc7a46e8ab849f2ccc9d427fcfd55979b43
Reviewed-on: https://chromium-review.googlesource.com/806324Reviewed-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@{#521505}

DEPS

@@ -74,7 +74,7 @@ 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': '7ffbcf909d365eb22c5e22b776aeac7b7472fbf3',
+  'skia_revision': '60b1b6e76e984228baa2e74513ea2174898c049b',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.