Loosen up assert in SkImage_Gpu::asTextureProxyRef

In the DDL world, the actual constraint is that the contexts have
the same ID. The old version was catching the case where an already
instantiated SkImage_Gpu was being drawn into a DDL.

Bug: 882457
Change-Id: I09ac0d5e176e8de5f5089d11d7495766c92f2450
Reviewed-on: https://skia-review.googlesource.com/153665
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed