Roll ANGLE 28a97ee..e8a7849

https://chromium.googlesource.com/angle/angle.git/+log/28a97ee..e8a7849

BUG=chromium:649101,chromium:649200
TBR=kbr@chromium.org,jmadill@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/2360203005
Cr-Commit-Position: refs/heads/master@{#420773}

DEPS

@@ -51,7 +51,7 @@ 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': '28a97ee11a38d9b4ac1e7adfb9343e228a5ed6ce',
+  'angle_revision': 'e8a7849613e5afa5b4ba223631d08278fbbae329',
   # 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.