Fix uint indices WebGL test to draw something. This test was specifying a draw with two indices instead of six. This wasn't producing any error on most configurations, but on Android it was producing a driver error that was only visible in Debug. BUG=angleproject:2086 Change-Id: I7c3cee4cc10d6c37e3bac8ed9fbc16ecb2cb9e63 Reviewed-on: https://chromium-review.googlesource.com/546539 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>