[skottie] Guard against asset cycles

Track assets being attached, and break cycles.

Bug: oss-fuzz:8220
Change-Id: I146cf35eba8cfea487c00544fe82f89c3a859803
Reviewed-on: https://skia-review.googlesource.com/127381
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
1 file changed