Dart: Avoid MojoResult and MojoHandleSignals constructors.

mojo/dart/test/validation_test.dart

 // Copyright 2015 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:convert';
 import 'dart:isolate';
 import 'dart:mojo.builtin' as builtin;
 import 'dart:typed_data';
 
@@ skipping 78 matching lines @@
     // TODO(zra): Make the error messages conform?
     // assert(e == expected);
     conformanceImpl.close();
     pipe.endpoints[0].close();
     pipe.endpoints[1].close();
     handles.forEach((h) => h.close());
     completer.completeError(null);
   });
 
   var length = (test.data == null) ? 0 : test.data.lengthInBytes;
-  var r = pipe.endpoints[1].write(test.data, length, handles);
-  assert(r.isOk);
+  int r = pipe.endpoints[1].write(test.data, length, handles);
+  assert(r == MojoResult.kOk);
 
   return completer.future.then((_) {
     assert(expected == "PASS");
     return conformanceImpl.close().then((_) {
       pipe.endpoints[0].close();
       pipe.endpoints[1].close();
       handles.forEach((h) => h.close());
     });
   }, onError: (e) {
     // Do nothing.
@@ skipping 16 matching lines @@
     try {
       await runTest(name, parser.parse(data), expected);
       print('$name PASSED.');
     } catch (e) {
       print('$name FAILED: $e');
     }
   }
   // TODO(zra): Add integration tests when they no longer rely on Client=
   MojoHandle.reportLeakedHandles();
 }