Roll src/third_party/angle/ 57d9cbb67..9aef81c7c (2 commits)

https://chromium.googlesource.com/angle/angle.git/+log/57d9cbb67f2d..9aef81c7cec0

$ git log 57d9cbb67..9aef81c7c --date=short --no-merges --format='%ad %ae %s'
2018-04-30 oetuaho Validate blitFramebuffer for overflows on all platforms
2018-04-26 oetuaho Clean up BlitGL

Created with:
  roll-dep src/third_party/angle
BUG=chromium:830046,chromium:830046


The AutoRoll server is located here: https://angle-chromium-roll.skia.org

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
TBR=cwallez@chromium.org

Change-Id: If5d19b20e6dc7096d7724d9fac6702427f560351
Reviewed-on: https://chromium-review.googlesource.com/1039067Reviewed-by: angle-chromium-autoroll <angle-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: angle-chromium-autoroll <angle-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#555350}

DEPS

@@ -108,7 +108,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
-  'angle_revision': '57d9cbb67f2d787e5236aebc0a3d48c5e0c922bd',
+  'angle_revision': '9aef81c7cec0989b9f8a072082d946989d59b541',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.