Dart: Avoid MojoResult and MojoHandleSignals constructors.

examples/dart/netcat/lib/main.dart

 #!mojo mojo:dart_content_handler
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:core';
 import 'dart:typed_data';
 
 import 'package:mojo/application.dart';
@@ skipping 106 matching lines @@
     }
 
     // TODO(vtl): Handle the send data pipe being full (or closed).
     _socketSender
         .write(new ByteData.view(_writeBuffer.buffer, 0, p.bytesRead.length));
 
     _startReadingFromTerminal();
   }
 
   void _onSocketReceiverEvent(List<int> event) {
-    var mojoSignals = new MojoHandleSignals(event[1]);
+    int mojoSignals = event[1];
     var shouldShutDown = false;
-    if (mojoSignals.isReadable) {
+    if (MojoHandleSignals.isReadable(mojoSignals)) {
       var numBytesRead = _socketReceiver.read(_readBuffer);
-      if (_socketReceiver.status.isOk) {
+      if (_socketReceiver.status == MojoResult.kOk) {
         assert(numBytesRead > 0);
         _terminal.ptr
             .write(_readBuffer.buffer.asUint8List(0, numBytesRead), 0,
                 files.Whence.FROM_CURRENT)
             .catchError((e) {
           _shutDown();
         });
         _socketReceiverEventSubscription.enableReadEvents();
       } else {
         shouldShutDown = true;
       }
-    } else if (mojoSignals.isPeerClosed) {
+    } else if (MojoHandleSignals.isPeerClosed(mojoSignals)) {
       shouldShutDown = true;
     } else {
-      throw 'Unexpected handle event: $mojoSignals';
+      String signals = MojoHandleSignals.string(mojoSignals);
+      throw 'Unexpected handle event: $signals';
     }
     if (shouldShutDown) {
       _shutDown();
     }
   }
 
   void _shutDown() {
     if (_socketReceiverEventSubscription != null) {
       ignoreFuture(_socketReceiverEventSubscription.close());
       _socketReceiverEventSubscription = null;
@@ skipping 76 matching lines @@
 }
 
 main(List args) {
   MojoHandle appHandle = new MojoHandle(args[0]);
   String url = args[1];
   new NetcatApplication.fromHandle(appHandle)
     ..onError = ((Object e) {
       MojoHandle.reportLeakedHandles();
     });
 }