Timer queries without context virtualization are now supported in the
Direct3D11 backend. Only the elapsed time portion of the GL extension is
supported though due to limitations of D3D11 preventing a reliable
implementation of the timestamp functionality. As a result of this, the
counter bits for the timestamp is set to 0 and any queries of the
timestamp will always return 0.

BUG=angleproject:657

Change-Id: I51ca1a1a6bd6bc13155cebeacdca414b764db168
Reviewed-on: https://chromium-review.googlesource.com/325780Reviewed-by: Jamie Madill <jmadill@chromium.org>