Add an EGL extension to disable GL extensions by default. BUG=angleproject:2404 Change-Id: I2667ddc92d5c9ef6e0ef115f2fdf0c3d3643d945 Reviewed-on: https://chromium-review.googlesource.com/962702 Reviewed-by: Frank Henigman <fjhenigman@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>