Queries in D3D11 are now virtualized such that they work as expected with
multiple contexts. Timer queries now only time the operations that their
context is responsible for and the operations of other contexts are
ignored.

BUG=angleproject:657

Change-Id: I667de594bdb5831d126d5801c0e692ded4c88bf4
Reviewed-on: https://chromium-review.googlesource.com/327150Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Ian Ewell <ewell@google.com>