Add missing functions to ListMixin.

tests/corelib/list_insert_test.dart

 // 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.
 
 import 'package:expect/expect.dart';
+import 'dart:collection';
 
-void main() {
-  // Normal modifiable list.
-  var l1 = [0, 1, 2, 3, 4];
+class MyList extends ListBase {
+  List list;
+  MyList(this.list);
 
+  get length => list.length;
+  set length(val) { list.length = val; }
+
+  operator [](index) => list[index];
+  operator []=(index, val) => list[index] = val;
+
+  String toString() => "[" + join(", ") + "]";
+}
+
+// l1 must be a modifiable list with 5 elements from 0 to 4.
+void testModifiableList(l1) {
   bool checkedMode = false;
   assert(checkedMode = true);
 
   // Index must be integer and in range.
   Expect.throws(() { l1.insert(-1, 5); },
                 (e) => e is RangeError,
                 "negative");
   Expect.throws(() { l1.insert(6, 5); },
                 (e) => e is RangeError,
                 "too large");
   Expect.throws(() { l1.insert(null, 5); });
   Expect.throws(() { l1.insert("1", 5); });
   Expect.throws(() { l1.insert(1.5, 5); });
 
   l1.insert(5, 5);
   Expect.equals(6, l1.length);
   Expect.equals(5, l1[5]);
   Expect.equals("[0, 1, 2, 3, 4, 5]", l1.toString());
 
   l1.insert(0, -1);
   Expect.equals(7, l1.length);
   Expect.equals(-1, l1[0]);
   Expect.equals("[-1, 0, 1, 2, 3, 4, 5]", l1.toString());
+}
+
+void main() {
+  // Normal modifiable list.
+  testModifiableList([0, 1, 2, 3, 4]);
+  testModifiableList(new MyList([0, 1, 2, 3, 4]));
 
   // Fixed size list.
   var l2 = new List(5);
   for (var i = 0; i < 5; i++) l2[i] = i;
   Expect.throws(() { l2.insert(2, 5); },
                 (e) => e is UnsupportedError,
                 "fixed-length");
 
   // Unmodifiable list.
   var l3 = const [0, 1, 2, 3, 4];
   Expect.throws(() { l3.insert(2, 5); },
                 (e) => e is UnsupportedError,
                 "unmodifiable");
 
   // Empty list is not special.
   var l4 = [];
   l4.insert(0, 499);
   Expect.equals(1, l4.length);
   Expect.equals(499, l4[0]);
 }