Reword the documentation for StreamQueue.cancel.

lib/src/stream_queue.dart

 // Copyright (c) 2015, 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.
 
 library async.stream_events;
 
 import 'dart:async';
 import 'dart:collection';
 
 import "subscription_stream.dart";
@@ skipping 205 matching lines @@
     throw _failClosed();
   }
 
   /// Cancels the underlying stream subscription.
   ///
   /// If [immediate] is `false` (the default), the cancel operation waits until
   /// all previously requested events have been processed, then it cancels the
   /// subscription providing the events.
   ///
   /// If [immediate] is `true`, the subscription is instead canceled
-  /// immediately. Any pending events are completed as though the underlying
-  /// stream had closed.
+  /// immediately. Any pending events complete with a 'closed'-event, as though
+  /// the stream had closed by itself.
   ///
   /// The returned future completes with the result of calling
   /// `cancel`.
   ///
   /// After calling `cancel`, no further events can be requested.
   /// None of [next], [rest], [skip], [take] or [cancel] may be
   /// called again.
   Future cancel({bool immediate: false}) {
     if (_isClosed) throw _failClosed();
     _isClosed = true;
@@ skipping 383 matching lines @@
       _completer.complete(true);
       return true;
     }
     return false;
   }
 
   void close(_) {
     _completer.complete(false);
   }
 }