Roll src/third_party/skia 656f2cd:c5e15a1

Summary of changes available at:
https://chromium.googlesource.com/skia/+log/656f2cd..c5e15a1

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

Review URL: https://codereview.chromium.org/618463002

Cr-Commit-Position: refs/heads/master@{#297279}

DEPS

@@ -35,7 +35,7 @@ vars = {
   'boringssl_git': 'https://boringssl.googlesource.com',
   'libvpx_revision': 'efe9712d52c2d216fb3d1ceb508b8148847a7e4b',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
-  'skia_revision': '656f2cd5588fabde2bbc2bd42763beb1347fc491',
+  'skia_revision': 'c5e15a1afab2621e860a251c3fcf5917867ad49f',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.