Allow Object when doing lookups.

sdk/lib/core/uri.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 dart.core;
 
 /**
  * A parsed URI, as specified by RFC-3986, http://tools.ietf.org/html/rfc3986.
  */
 class Uri {
@@ skipping 1084 matching lines @@
                 //               abcdefghijklmno
       0xfffe,   // 0x60 - 0x6f  0111111111111111
                 //              pqrstuvwxyz   ~
       0x47ff];  // 0x70 - 0x7f  1111111111100010
 }
 
 class _UnmodifiableMap<K, V> implements Map<K, V> {
   final Map _map;
   const _UnmodifiableMap(this._map);
 
-  bool containsValue(V value) => _map.containsValue(value);
-  bool containsKey(K key) => _map.containsKey(key);
-  V operator [](K key) => _map[key];
+  bool containsValue(Object value) => _map.containsValue(value);
+  bool containsKey(Object key) => _map.containsKey(key);
+  V operator [](Object key) => _map[key];
   void operator []=(K key, V value) {
     throw new UnsupportedError("Cannot modify an unmodifiable map");
   }
   V putIfAbsent(K key, V ifAbsent()) {
     throw new UnsupportedError("Cannot modify an unmodifiable map");
   }
   addAll(Map other) {
     throw new UnsupportedError("Cannot modify an unmodifiable map");
   }
-  V remove(K key) {
+  V remove(Object key) {
     throw new UnsupportedError("Cannot modify an unmodifiable map");
   }
   void clear() {
     throw new UnsupportedError("Cannot modify an unmodifiable map");
   }
   void forEach(void f(K key, V value)) => _map.forEach(f);
   Iterable<K> get keys => _map.keys;
   Iterable<V> get values => _map.values;
   int get length => _map.length;
   bool get isEmpty => _map.isEmpty;
   bool get isNotEmpty => _map.isNotEmpty;
 }