These accessors do not make any use of the interpreter, hence we can
define them on the WasmInstanceObject alone. This will allow to reuse
them for other (non-interpreted) frames.

R=mstarzinger@chromium.org

Bug: v8:9676
Change-Id: Iff8b665a4c25581b934c25b66a13cebe044cb02c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1875097Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64511}