Enable WebGL 2 by default on Android

BUG=673426,295792,641635
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2717003002
Cr-Commit-Position: refs/heads/master@{#453293}
1 file changed