Rename blahHandler to onBlah throughout dart:io.

tests/standalone/src/FileOutputStreamTest.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.
 // Testing file input stream, VM-only, standalone test.
 
 #import("dart:io");
 #import("dart:isolate");
 
 void testOpenOutputStreamSync() {
   Directory tempDirectory = new Directory('');
 
   // Create a port for waiting on the final result of this test.
   ReceivePort done = new ReceivePort();
   done.receive((message, replyTo) {
     tempDirectory.deleteSync();
     done.close();
   });
 
   tempDirectory.createTempSync();
   String fileName = "${tempDirectory.path}/test";
   File file = new File(fileName);
   file.createSync();
   OutputStream x = file.openOutputStream();
   x.write([65, 66, 67]);
   x.close();
-  x.closeHandler = () {
+  x.onClose = () {
     file.deleteSync();
     done.toSendPort().send("done");
   };
 }
 
 
 void testOutputStreamNoPendingWrite() {
   Directory tempDirectory = new Directory('');
 
   // Create a port for waiting on the final result of this test.
   ReceivePort done = new ReceivePort();
   done.receive((message, replyTo) {
     tempDirectory.delete();
-    tempDirectory.deleteHandler = () {
+    tempDirectory.onDelete = () {
       done.close();
     };
   });
 
   tempDirectory.createTemp();
-  tempDirectory.createTempHandler = () {
+  tempDirectory.onCreateTemp = () {
     String fileName = "${tempDirectory.path}/test";
     File file = new File(fileName);
     file.create();
-    file.createHandler = () {
+    file.onCreate = () {
       OutputStream stream = file.openOutputStream();
       final total = 100;
       var count = 0;
-      stream.noPendingWriteHandler = () {
+      stream.onNoPendingWrite = () {
         stream.write([count++]);
         if (count == total) {
           stream.close();
         }
-        stream.closeHandler = () {
+        stream.onClose = () {
           List buffer = new List<int>(total);
           File fileSync = new File(fileName);
           var openedFile = fileSync.openSync();
           openedFile.readListSync(buffer, 0, total);
           for (var i = 0; i < total; i++) {
             Expect.equals(i, buffer[i]);
           }
           openedFile.closeSync();
           fileSync.deleteSync();
           done.toSendPort().send("done");
         };
       };
     };
   };
 }
 
 
 main() {
   testOpenOutputStreamSync();
   testOutputStreamNoPendingWrite();
 }