Add a flag to help platform ports bootstrap V8

src/runtime/runtime-internal.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include <memory>
 
 #include "src/arguments.h"
 #include "src/ast/prettyprinter.h"
@@ skipping 567 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_IsWasmObject) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_CHECKED(Object, object, 0);
   bool is_wasm_object =
       object->IsJSObject() && wasm::IsWasmObject(JSObject::cast(object));
   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