Roll src/third_party/skia/ 50d4a6a66..48b56688e (3 commits)

https://skia.googlesource.com/skia.git/+log/50d4a6a66190..48b56688e8f5

$ git log 50d4a6a66..48b56688e --date=short --no-merges --format='%ad %ae %s'
2018-02-16 caryclark report ignore attr once only
2018-02-15 jvanverth Add full scaling for color emoji.
2018-02-16 scroggo Ensure all rows of a gif are initialized

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=caryclark@chromium.org

Change-Id: Ia17092ecbdf4989a2797983db70fbaf59153fe2a
Reviewed-on: https://chromium-review.googlesource.com/924305Reviewed-by: skia-chromium-autoroll <skia-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: skia-chromium-autoroll <skia-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#537395}

DEPS

@@ -79,7 +79,7 @@ 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': '50d4a6a661909a36d259e3c6007337af8050a9fe',
+  'skia_revision': '48b56688e8f53346435f80b20aca2c0f1b7b54c7',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.