Implement List<T> operations on dom types via manual mixins.

client/dom/src/_Lists.dart

 // Copyright (c) 2011, 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.
 
 class _Lists {
 
   /**
    * Returns the index in the array [a] of the given [element], starting
    * the search at index [startIndex] to [endIndex] (exclusive).
    * Returns -1 if [element] is not found.
@@ skipping 28 matching lines @@
     if (startIndex >= a.length) {
       startIndex = a.length - 1;
     }
     for (int i = startIndex; i >= 0; i--) {
       if (a[i] == element) {
         return i;
       }
     }
     return -1;
   }
+
+  /**
+   * Returns a sub list copy of this list, from [start] to
+   * [:start + length:].
+   * Returns an empty list if [length] is 0.
+   * Throws an [IllegalArgumentException] if [length] is negative.
+   * Throws an [IndexOutOfRangeException] if [start] or
+   * [:start + length:] are out of range.
+   */
+  static List getRange(List a, int start, int length, List accumulator) {
+    if (length < 0) throw new IllegalArgumentException('length');
+    if (start < 0) throw new IndexOutOfRangeException(start);
+    int end = start + length;
+    if (end > a.length) throw new IndexOutOfRangeException(end);
+    for (int i = start; i < end; i++) {
+      accumulator.add(a[i]);
+    }
+    return accumulator;
+  }
 }