This CL fixes a memory leak in the interpreter. The leak was caused by
a cycle the object graph that was rooted with a global object. The
cycle was the following:

A global handle, owned by the interpreter -> reference stack of the
Interpreter -> ref.func element (WasmExportedFunction) ->
WasmInstanceObject -> WasmDebugInfo -> InterpreterHandle -> Interpreter

With this CL we get rid of the global handle. Instead we store the stack
in the WasmDebugInfo. We then have to load the reference stack every time
we enter the Interpreter and want access the reference stack.

R=mstarzinger@chromium.org

Bug: chromium:1000610
Change-Id: If8995725f7ec35862b2f99a07582c861027daaf1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1800582
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63953}