Add an OutputStream.closed getter.

runtime/bin/output_stream.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.
 
 /**
  * Output streams are used to write data sequentially to a data
  * destination e.g. a connected socket or an open file.
  *
  * An output stream provides internal buffering of the data written
  * through all calls to [write] and [writeFrom] if data cannot be
@@ skipping 40 matching lines @@
   bool writeString(String string, [Encoding encoding]);
 
   /**
    * Flushes data from any internal buffers as soon as possible. Note
    * that the actual meaning of calling [flush] will depend on the
    * actual type of the underlying communication channel.
    */
   void flush();
 
   /**
-   * Indicate that all data has been written to the output
-   * stream. When all data has been written to the communication
-   * channel it will be closed.
+   * Signal that no more data will be written to the output stream. When all
+   * buffered data has been written out to the communication channel, the
+   * channel will be closed and the [onClosed] callback will be called.
    */
   void close();
 
   /**
    * Close the communication channel immediately ignoring any buffered
    * data.
    */
   void destroy();
 
   /**
+   * Returns whether the stream has been closed by calling close(). If true, no
+   * more data may be written to the output stream, but there still may be
+   * buffered data that has not been written to the communication channel. The
+   * onClosed handler will only be called once all data has been written out.
+   */
+  bool get closed();
+
+  /**
    * Sets the handler that gets called when the internal OS buffers
    * have been flushed. This callback can be used to keep the rate of
    * writing in sync with the rate the system can write data to the
    * underlying communication channel.
    */
   void set onNoPendingWrites(void callback());
 
   /**
-   * Sets the handler that gets called when the underlying
-   * communication channel has been closed and no more data can be
-   * send.
+   * Sets the handler that gets called when the underlying communication channel
+   * has been closed and all the buffered data has been sent.
    */
   void set onClosed(void callback());
 
   /**
    * Sets the handler that gets called when the underlying
    * communication channel gets into some kind of error situation.
    */
   void set onError(void callback(e));
 }