Fix a VM test loading bug.

lib/src/runner/loader.dart

 // Copyright (c) 2015, 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.
 
 library test.runner.loader;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
@@ skipping 164 matching lines @@
 
   /// Load the test suite at [path] in VM isolate.
   ///
   /// [metadata] is the suite-level metadata for the test.
   Future<Suite> _loadVmFile(String path, Metadata metadata) async {
     var receivePort = new ReceivePort();
 
     var isolate;
     try {
       if (_pubServeUrl != null) {
-        var url = _pubServeUrl.resolve(
-            p.relative(path, from: 'test') + '.vm_test.dart');
+        var url = _pubServeUrl.resolveUri(
+            p.toUri(p.relative(path, from: 'test') + '.vm_test.dart'));
 
         // TODO(nweiz): Remove new Future.sync() once issue 23498 has been fixed
         // in two stable versions.
         await new Future.sync(() async {
           try {
             isolate = await dart.spawnUri(url, {
               'reply': receivePort.sendPort,
               'metadata': metadata.serialize()
             }, checked: true);
           } on IsolateSpawnException catch (error) {
@@ skipping 58 matching lines @@
       for (var isolate in _isolates) {
         isolate.kill();
       }
       _isolates.clear();
 
       if (!_browserServerThunk.hasRun) return;
       await (await _browserServer).close();
     });
   }
 }