[stubs] Unify (and optimize) implementation of ToObject.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index 07ba01f957ad108153a546656c61ce1d9a418a2f..f77216e798bc54a11df42cc7a75f2ca54b31a416 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -1461,5 +1461,19 @@ RUNTIME_FUNCTION(Runtime_DefineSetterPropertyUnchecked) {
                                setter, attrs));
   return isolate->heap()->undefined_value();
 }
+
+
+RUNTIME_FUNCTION(Runtime_ToObject) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
+  Handle<JSReceiver> receiver;
+  if (JSReceiver::ToObject(isolate, object).ToHandle(&receiver)) {
+    return *receiver;
+  }
+  THROW_NEW_ERROR_RETURN_FAILURE(
+      isolate, NewTypeError(MessageTemplate::kUndefinedOrNullToObject));
+}
+
 }  // namespace internal
 }  // namespace v8