The error happens when a RWTexture is used in shader. However, there is
no resource binding to it. We should clear the corresponding UAV in case
the previous view type is a bufer not a texture.

Meanwhile, this patch removes clearSRVs/clearUAVs since we use
unsetConflictingSRVs/unsetConflictingUAVs to do the similar thing.

Bug: angleproject:3512, angleproject:3548
Change-Id: I01752bb9bc6aca5b767599639c4dc613b4e2e2d2
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1662017Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jiajia Qin <jiajia.qin@intel.com>