Avoid using GL_EXT_disjoint_timer_query extension on Nexus 9 in WebView.
Until the GPU blacklist is working on Android WebView, manually stop
using the GL_EXT_disjoint_timer_query extension when running the WebGL
conformance tests in Android's WebView. This workaround is only needed
on the Nexus 9, but it's currently difficult to limit it to just that
device.
BUG=499928, 499555
TBR=boliu@chromium.org
NOTRY=true
Review URL: https://codereview.chromium.org/
1181833008
Cr-Commit-Position: refs/heads/master@{#334773}