Restructure tiled image test

Skip needlessly recreating some large objects.

Bug: b/267656937
Change-Id: I4643d30773c024b3c6926e8d133f83b246c3b3fb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/708391
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed