Add List.insert.

pkg/serialization/lib/src/serialization_rule.dart

 // Copyright (c) 2012, 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.
 
 part of serialization;
 
 // TODO(alanknight): We should have an example and tests for subclassing
 // serialization rule rather than using the hard-coded ClosureToMap rule. And
 // possibly an abstract superclass that's designed to be subclassed that way.
 /**
@@ skipping 534 matching lines @@
   // These operations are all invalid
   _throw() {
     throw new UnsupportedError("Not modifiable");
   }
   operator []=(x, y) => _throw();
   add(x) => _throw();
   addLast(x) => _throw();
   addAll(x) => _throw();
   sort([f]) => _throw();
   clear() => _throw();
+  insertAt(x, y) => _throw();
   removeAt(x) => _throw();
   remove(x) => _throw();
   removeLast() => _throw();
   removeAll(x) => _throw();
   retainAll(x) => _throw();
   removeMatching(x) => _throw();
   retainMatching(x) => _throw();
   getRange(x, y) => _throw();
   setRange(x, y, z, [a]) => _throw();
   removeRange(x, y) => _throw();
   insertRange(x, y, [z]) => _throw();
   get reversed => _throw();
   void set length(x) => _throw();
 }