Rename unsubscribe to cancel.

tests/lib/async/slow_consumer2_test.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.
 
 // VMOptions=--old_gen_heap_size=32
 
 import 'dart:async';
 import 'dart:isolate';
 
 const int KB = 1024;
 const int MB = KB * KB;
 const int GB = KB * KB * KB;
 
 class SlowConsumer extends StreamPipe {
   int receivedCount = 0;
   final int bytesPerSecond;
   final int bufferSize;
   final List bufferedData = [];
   int usedBufferSize = 0;
 
   SlowConsumer(int this.bytesPerSecond, int this.bufferSize);
 
   Future bind(Stream stream) {
     Completer result = new Completer();
     var subscription;
-    subscription = stream.subscribe(
-      onData: (List<int> data) {
+    subscription = stream.listen(
+      (List<int> data) {
         receivedCount += data.length;
         usedBufferSize += data.length;
         bufferedData.add(data);
         int currentBufferedDataLength = bufferedData.length;
         if (usedBufferSize > bufferSize) {
           subscription.pause();
           usedBufferSize = 0;
           int ms = data.length * 1000 ~/ bytesPerSecond;
           new Timer(ms, (_) {
             for (int i = 0; i < currentBufferedDataLength; i++) {
@@ skipping 53 matching lines @@
   // file). If the consumer doesn't pause the data-provider it will run out of
   // heap-space.
 
   new DataProvider(800 * MB, 100 * MB, 1 * MB)
     .pipe(new SlowConsumer(200 * MB, 5 * MB))
     .then((count) {
       port.close();
       Expect.equals(100 * MB, count);
     });
 }