This completes the refactor for the D3D9/D3D11 back-ends.

Bug: angleproject:2752
Change-Id: Ie35a925f75c902d8f9fdab6bc33b3bb9c937f85b
Reviewed-on: https://chromium-review.googlesource.com/1167209
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>