Roll src/third_party/skia a60b2ea:1629118

Summary of changes available at:
https://chromium.googlesource.com/skia/+log/a60b2ea..1629118

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

Review URL: https://codereview.chromium.org/801903002

Cr-Commit-Position: refs/heads/master@{#308177}

DEPS

@@ -44,7 +44,7 @@ vars = {
   'boringssl_git': 'https://boringssl.googlesource.com',
   'libvpx_revision': 'd3f3dcefb055656807e8a2f65a322bbb13cd05a4',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
-  'skia_revision': 'a60b2ead80c5442f35fb9109380ead98865e61be',
+  'skia_revision': '16291189cef3d7855faa85ca70a0b9c1add15fbb',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.