We were missing both the correct SRV parameter, as well as the full
computation of the mip level in the HLSL.

BUG=angleproject:1208

Change-Id: I345b1e0895495654de3863c4ebcc395d9b7371b9
Reviewed-on: https://chromium-review.googlesource.com/312060Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>