Roll src/third_party/skia 7839915:d12af70

Summary of changes available at:
https://chromium.googlesource.com/skia/+log/7839915..d12af70

CQ_EXTRA_TRYBOTS=tryserver.blink:linux_blink_rel,linux_blink_dbg
TBR=rmistry@google.com

Review URL: https://codereview.chromium.org/666633002

Cr-Commit-Position: refs/heads/master@{#300188}

DEPS

@@ -44,7 +44,7 @@ vars = {
   'boringssl_git': 'https://boringssl.googlesource.com',
   'libvpx_revision': 'efe9712d52c2d216fb3d1ceb508b8148847a7e4b',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
-  'skia_revision': '783991585be67da3286680d850a99c5410885965',
+  'skia_revision': 'd12af70baf08c90491d11b4c55d5f6499fa84a0e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.