Update flag checks when validating surface being assigned to proxy.

Bug: skia:7748
Change-Id: Id87c0b1be2efbdefd96740e9591fd102e09b4d95
Reviewed-on: https://skia-review.googlesource.com/123423
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
9 files changed