Roll WebGL 937acaa..e3488c3

https://chromium.googlesource.com/external/khronosgroup/webgl.git/+log/937acaa..e3488c3

BUG=
TEST=bots
TBR=kbr@chromium.org
NOTRY=true
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

Review-Url: https://codereview.chromium.org/2174253003
Cr-Commit-Position: refs/heads/master@{#407483}

DEPS

@@ -178,7 +178,7 @@ deps = {
     Var('chromium_git') + '/external/bidichecker/lib.git' + '@' + '97f2aa645b74c28c57eca56992235c79850fa9e0',
 
   'src/third_party/webgl/src':
-   Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + '937acaae1251a1e338bafe1995c0d54cb7142c60',
+   Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + 'e3488c31e13202c8d41b92eb6b7358cd23e5e004',
 
   'src/third_party/webdriver/pylib':
     Var('chromium_git') + '/external/selenium/py.git' + '@' + '5fd78261a75fe08d27ca4835fb6c5ce4b42275bd',