[wasm][gc] Add code ref scope for fuzzers

A testing method was missing a code ref scope, making fuzzers fail.

R=mstarzinger@chromium.org

Bug: chromium:952759
Change-Id: Ib9d485fad85f66ca358a769a4e52777f68367991
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1571605Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60909}

test/common/wasm/wasm-module-runner.cc

@@ -61,6 +61,8 @@ bool InterpretWasmModuleForTesting(Isolate* isolate,
                                    Handle<WasmInstanceObject> instance,
                                    const char* name, size_t argc,
                                    WasmValue* args) {
+  HandleScope handle_scope(isolate);  // Avoid leaking handles.
+  WasmCodeRefScope code_ref_scope;
   MaybeHandle<WasmExportedFunction> maybe_function =
       GetExportedFunction(isolate, instance, "main");
   Handle<WasmExportedFunction> function;