Removing this allows many angle end2end tests to run without hitting any
UNIMPLEMENTEDs.

BUG=angleproject:882

Change-Id: Idb55fae7b6fc7b23bc85d0bf376499f28669d771
Reviewed-on: https://chromium-review.googlesource.com/263250Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>