Roll ANGLE 47bf2dc..1f9d684

https://chromium.googlesource.com/angle/angle.git/+log/47bf2dc..1f9d684

BUG=chromium:767279,chromium:725308,chromium:765321,chromium:655534

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

Change-Id: I794ad67e2a1ef672855c65eef94959800cba9477
Reviewed-on: https://chromium-review.googlesource.com/677428Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503529}

DEPS

@@ -53,7 +53,7 @@ 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': '47bf2dc53c4cd561eae1522131ab15aec3038d5c',
+  'angle_revision': '1f9d68437c9d3fd1bcb8fffff84fdd29d1857919',
   # 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.