Roll src/third_party/skia adf9990:b502ee3

Summary of changes available at:
https://chromium.googlesource.com/skia/+log/adf9990..b502ee3

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=egdaniel@google.com

Review URL: https://codereview.chromium.org/1027803002

Cr-Commit-Position: refs/heads/master@{#321595}

DEPS

@@ -42,7 +42,7 @@ vars = {
   'boringssl_git': 'https://boringssl.googlesource.com',
   'libvpx_revision': '00cf1b1656d1669e1874fa8c70c493e2c3accad5',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
-  'skia_revision': 'adf9990cb56ca389f37f02ac637496083b3c3cfc',
+  'skia_revision': 'b502ee3acea9bca87ab75de808b4a7eda67aadff',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.