This is a useful workaround for testing/diagnostics.
Disabled by default.

Bug: angleproject:5007
Change-Id: If459f60ae7f8a2cd4ea934fe3e54d890387d57db
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2385933
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>