Roll src/third_party/skia/ 426a24592..a42405aa5 (2 commits).

https://chromium.googlesource.com/skia.git/+log/426a2459290a..a42405aa522c

$ git log 426a24592..a42405aa5 --date=short --no-merges --format='%ad %ae %s'
2016-09-09 borenet Fix issues in assets scripts
2016-09-09 halcanary SkPDF: implement drawTextBlob()

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel
TBR=caryclark@google.com

Review-Url: https://codereview.chromium.org/2321403002
Cr-Commit-Position: refs/heads/master@{#417579}

DEPS

@@ -36,7 +36,7 @@ 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': '426a2459290a57bf32151f042fe5cd67da61d02f',
+  'skia_revision': 'a42405aa522cd33292b9817da460e9f29e00a201',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.