Check CallSite arguments more rigorously

src/wasm/wasm-module.h

Index: src/wasm/wasm-module.h
diff --git a/src/wasm/wasm-module.h b/src/wasm/wasm-module.h
index e7e2fdcd4b779605f12fef77780940d4214c66cf..925cbf0b4c050fc4bf27ce3a7e98aced10149caa 100644
--- a/src/wasm/wasm-module.h
+++ b/src/wasm/wasm-module.h
@@ -329,6 +329,13 @@ int32_t CompileAndRunWasmModule(Isolate* isolate, WasmModule* module);
 MaybeHandle<String> GetWasmFunctionName(Handle<JSObject> wasm,
                                         uint32_t func_index);
 
+// Check whether the given object is a wasm object.
+// This checks the number and type of internal fields, so it's not 100 percent
+// secure. If it turns out that we need more complete checks, we could add a
+// special marker as internal field, which will definitely never occur anywhere
+// else.
+bool IsWasmObject(Handle<JSObject> object);
+
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8