We optimize away type upcasts for nominal types in WasmFullDecoder.
Upcasts trivially hold for nominal types, which is not the case for
structural types. Note that we already optimize away trivially-failing
checks (when types are unrelated) for both nominal and structural types.

Bug: v8:7748
Change-Id: I720c9803cb8b4071aa4bae112ce06d587b7a68fa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3306984
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78201}