Another case of the VM getting a path into Uri.parse.

runtime/bin/builtin.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.
 
 library builtin;
 import 'dart:io';
 import 'dart:async';
 import 'dart:convert';
 // import 'root_library'; happens here from C Code
 
@@ skipping 344 matching lines @@
                  "${_numOutstandingLoadRequests} requests remaining");
   if (_numOutstandingLoadRequests == 0) {
     _signalDoneLoading();
   }
 }
 
 
 // Asynchronously loads source code through an http or file uri.
 _loadSourceAsync(int tag, String uri, String libraryUri) {
   var filePath = _filePathFromUri(uri);
-  Uri sourceUri = new Uri.file(filePath);
+  Uri sourceUri = _uriFromPathOrUri(filePath);
   _numOutstandingLoadRequests++;
   _logResolution("_loadLibrarySource($uri), "
                  "${_numOutstandingLoadRequests} requests outstanding");
   if (sourceUri.scheme == 'http') {
     _httpGet(sourceUri, (data) {
       var text = UTF8.decode(data);
       _loadLibrarySource(tag, uri, libraryUri, text);
     });
   } else {
     var sourceFile = new File(filePath);
@@ skipping 45 matching lines @@
   } else if (Platform.isWindows) {
     filename = '$name.dll';
   } else {
     _logResolution(
         'Native extensions not supported on ${Platform.operatingSystem}');
     throw 'Native extensions not supported on ${Platform.operatingSystem}';
   }
 
   return [path, filename, name];
 }