Allow Object when doing lookups.

runtime/lib/growable_array.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.
 
 class _GrowableObjectArray<T> implements List<T> {
   static final int _classId = (new _GrowableObjectArray(0))._cid;
 
   void insert(int index, T element) {
     if (index < 0 || index > length) {
       throw new RangeError.range(index, 0, length);
@@ skipping 194 matching lines @@
     if (length > 0) return this[length - 1];
     throw new StateError("No elements");
   }
 
   T get single {
     if (length == 1) return this[0];
     if (length == 0) throw new StateError("No elements");
     throw new StateError("More than one element");
   }
 
-  int indexOf(T element, [int start = 0]) {
+  int indexOf(Object element, [int start = 0]) {
     return IterableMixinWorkaround.indexOfList(this, element, start);
   }
 
-  int lastIndexOf(T element, [int start = null]) {
+  int lastIndexOf(Object element, [int start = null]) {
     return IterableMixinWorkaround.lastIndexOfList(this, element, start);
   }
 
   void _grow(int new_length) {
     var new_data = new _ObjectArray(new_length);
     for (int i = 0; i < length; i++) {
       new_data[i] = this[i];
     }
     _setData(new_data);
   }
 
   // Collection interface.
 
-  bool contains(T element) {
+  bool contains(Object element) {
     return IterableMixinWorkaround.contains(this, element);
   }
 
   void forEach(f(T element)) {
     int initialLength = length;
     for (int i = 0; i < length; i++) {
       f(this[i]);
       if (length != initialLength) throw new ConcurrentModificationError(this);
     }
   }
@@ skipping 105 matching lines @@
   }
 
   Set<T> toSet() {
     return new Set<T>.from(this);
   }
 
   Map<int, T> asMap() {
     return IterableMixinWorkaround.asMapList(this);
   }
 }