ANGLE currently blocks resources sharing if ANGLE was initialized using
EGL_PLATFORM_ANGLE_DEVICE_TYPE_WARP_ANGLE. This is to prevent applications
from trying to share resources between hardware D3D devices and WARP.

However, this prevents developers from deliberately initializing ANGLE
to run on WARP, and then sharing resources with an external WARP device.
ANGLE should support that scenario.

BUG=angleproject:1283

Change-Id: I86681355bf34f7fe3367261dd76c434a9fa60739
Reviewed-on: https://chromium-review.googlesource.com/317318Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tryjob-Request: Austin Kinross <aukinros@microsoft.com>
Tested-by: Jamie Madill <jmadill@chromium.org>