Roll src/third_party/skia/ 789fd9965..78e0aef61 (2 commits).
Roll src/third_party/skia/ 789fd9965..78e0aef61 (2 commits).

https://chromium.googlesource.com/skia.git/+log/789fd996599f..78e0aef610d7

$ git log 789fd9965..78e0aef61 --date=short --no-merges --format='%ad %ae %s'
2015-12-16 mtklein SSE 4.1 SrcOver blits: color32, blitmask.
2015-12-16 joshualitt Blacklist GLInstancedArraysBench on ipad

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=joshualitt@google.com

Review URL: https://codereview.chromium.org/1534543002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#365616}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk