This patch resolves one TODO that Support to translate instance uniform
block containing only a large array member to Structured buffer on D3D
backend when necessary.

Bug: angleproject:4205
Change-Id: If2cd6cf633080820ea33e52269d7d86cd587c9ee
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2114912
Commit-Queue: Xinghua Cao <xinghua.cao@intel.com>
Reviewed-by: Jiajia Qin <jiajia.qin@intel.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>