Allow Object when doing lookups.

sdk/lib/async/stream.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.
 
 part of dart.async;
 
 // -------------------------------------------------------------------
 // Core Stream types
 // -------------------------------------------------------------------
 
@@ skipping 289 matching lines @@
         result._setError(e);
       },
       onDone: () {
         result._setValue(value);
       },
       cancelOnError: true);
     return result;
   }
 
   /**
-   * Checks whether [match] occurs in the elements provided by this stream.
+   * Checks whether [needle] occurs in the elements provided by this stream.
    *
    * Completes the [Future] when the answer is known.
    * If this stream reports an error, the [Future] will report that error.
    */
-  Future<bool> contains(T match) {
+  Future<bool> contains(Object needle) {
     _FutureImpl<bool> future = new _FutureImpl<bool>();
     StreamSubscription subscription;
     subscription = this.listen(
         // TODO(ahe): Restore type when feature is implemented in dart2js
         // checked mode. http://dartbug.com/7733
         (/*T*/ element) {
           _runUserCode(
-            () => (element == match),
+            () => (element == needle),
             (bool isMatch) {
               if (isMatch) {
                 subscription.cancel();
                 future._setValue(true);
               }
             },
             _cancelAndError(subscription, future)
           );
         },
         onError: future._setError,
@@ skipping 907 matching lines @@
    *
    * If a [moveNext] call has been made, it will complete with `false` as value,
    * as will all further calls to [moveNext].
    *
    * If you need to stop listening for values before the stream iterator is
    * automatically closed, you must call [cancel] to ensure that the stream
    * is properly closed.
    */
   void cancel();
 }