Add internal operation that converts a growable list to a fixed list.

runtime/lib/internal_patch.dart

Index: runtime/lib/internal_patch.dart
diff --git a/runtime/lib/internal_patch.dart b/runtime/lib/internal_patch.dart
index c4618bc60b69a7cac8d7ddacd25c37ea3840f96a..90856cb33468ed2dc2f78764f3d4be3c19d05c66 100644
--- a/runtime/lib/internal_patch.dart
+++ b/runtime/lib/internal_patch.dart
@@ -1,3 +1,12 @@
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
+
+patch List makeListFixedLength(List growableList)
+    => _StaticClass.makeListFixedLength(growableList);
+
+// Making the native class static, not top-level.
+class _StaticClass {

[Ivan Posva, 2014/02/06 16:57:00]

Why is it necessary to jump through multiple hoops here?

[Lasse Reichstein Nielsen, 2014/02/07 12:55:25]

I had problems making the top-level patch function be a native function.
Making it forward to a class static method worked.
If there is a simpler way, I'd love to make it simpler!

[floitsch, 2014/02/07 15:13:13]

I guess it's issue 6997.

+  static List makeListFixedLength(List growableList)
+    native "GrowableList_toFixedLength";
+}