Revert "Revert "Allow linear 8888 surface contexts in GPU backend.""

This reverts commit 4ffdf3c67ff7f9ee66d56db02161d66fddd9fdf7.

Change-Id: I6c38328500ec9614b587121741e63c7b1a092c7d
Reviewed-on: https://skia-review.googlesource.com/107005
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
3 files changed