Remove fAssignedSurface from GrResourceAllocator::Interval

The surface on the proxy should be the source of truth here.

Bug: skia:10877
Change-Id: Id2126a259202be4c426f2cbf8f025ef69dd50551
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/384702
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
2 files changed