Skia roll 21e6135:700a78d

https://skia.googlesource.com/skia/+log/21e613505562368e7719215f824fa8b3b4be652d..700a78d72fdf4f09b28446818028b39f31e26b38

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

Review URL: https://codereview.chromium.org/525973002

Cr-Commit-Position: refs/heads/master@{#292819}

DEPS

@@ -38,7 +38,7 @@ vars = {
   # to update other nacl_*_revision's.
   'libvpx_revision': '982d14793a8e42d2fa5e6e5e34bede17b4ba67e3', # r291730
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
-  'skia_revision': '21e613505562368e7719215f824fa8b3b4be652d',
+  'skia_revision': '700a78d72fdf4f09b28446818028b39f31e26b38',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.