Roll ANGLE a818c32..a66779f

https://chromium.googlesource.com/angle/angle.git/+log/a818c32..a66779f

BUG=chromium:677841,chromium:644610

TBR=geofflang@chromium.org

TEST=bots

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2614063006
Cr-Commit-Position: refs/heads/master@{#442051}

DEPS

@@ -52,7 +52,7 @@ 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': 'a818c327fe6bb770c3a3621a985c4afd698ad0ab',
+  'angle_revision': 'a66779fcf2aeed8588bcc1ba6a3668d81e65bf3b',
   # 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.