Add a flag to help platform ports bootstrap V8

src/runtime/runtime-internal.cc

Index: src/runtime/runtime-internal.cc
diff --git a/src/runtime/runtime-internal.cc b/src/runtime/runtime-internal.cc
index 84cc2030283148de91c3ab5e35eaccfada3ae137..2ed57566328c95777707cda344d7ef60715bb884 100644
--- a/src/runtime/runtime-internal.cc
+++ b/src/runtime/runtime-internal.cc
@@ -585,5 +585,12 @@ RUNTIME_FUNCTION(Runtime_IsWasmObject) {
   return *isolate->factory()->ToBoolean(is_wasm_object);
 }
 
+RUNTIME_FUNCTION(Runtime_Typeof) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
+  return *Object::TypeOf(isolate, object);
+}
+
 }  // namespace internal
 }  // namespace v8