Revert "Revert "Expand partial render target write pixels workaround.""

New version limits the workaround to unorm configs.

This reverts commit fdd117025fb846771e9e47cbf825d9071745fa98.

Change-Id: I47a08a0ea4cf1acd88ca3c1bf9922cf0a8d215cc
Reviewed-on: https://skia-review.googlesource.com/19490
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
10 files changed