Roll src/third_party/skia/ 9bbfb6576..a129dfef2 (6 commits).

https://skia.googlesource.com/skia.git/+log/9bbfb657606d..a129dfef2aaa

$ git log 9bbfb6576..a129dfef2 --date=short --no-merges --format='%ad %ae %s'
2016-12-09 reed Revert "remove SK_SUPPORT_LEGACY_CLIP_REGIONOPS"
2016-12-08 herb Add the ability to use different mallocs.
2016-12-08 caryclark fix fuzzers
2016-12-08 reed remove SK_SUPPORT_LEGACY_CLIP_REGIONOPS
2016-12-08 jcgregorio Remove documentation about emboss.
2016-12-08 caryclark simplify bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
TBR=herb@google.com

Review-Url: https://codereview.chromium.org/2558853005
Cr-Commit-Position: refs/heads/master@{#437543}

DEPS

@@ -40,7 +40,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': '9bbfb657606d4c501dd4df13cc035cf38f7672c9',
+  'skia_revision': 'a129dfef2aaab0b5995cdf1ab7b2cdd41c29cf72',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.