Fix some analyzer warnings in dart:io.

sdk/lib/io/directory_impl.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.
 
 part of dart.io;
 
 class _Directory implements Directory {
   static const CREATE_REQUEST = 0;
   static const DELETE_REQUEST = 1;
   static const EXISTS_REQUEST = 2;
@@ skipping 80 matching lines @@
       }
     }
     if (future == null) {
       return new Future.value(notFound);
     } else {
       return future;
     }
   }
 
   Future<Directory> createRecursively() {
-    var path = new Path(path);
+    var path = new Path(this.path);
     var dirsToCreate = [];
     var terminator = path.isAbsolute ? '/' : '';
     while (path.toString() != terminator) {
       dirsToCreate.add(new Directory.fromPath(path));
       path = path.directoryPath;
     }
     return _computeExistingIndex(dirsToCreate).then((index) {
       var future;
       for (var i = index - 1; i >= 0 ; i--) {
         if (future == null) {
@@ skipping 20 matching lines @@
     request[1] = path;
     return _directoryService.call(request).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionOrErrorFromResponse(response, "Creation failed");
       }
       return this;
     });
   }
 
   void createRecursivelySync() {
-    var path = new Path(path);
+    var path = new Path(this.path);
     var dirsToCreate = [];
     var terminator = path.isAbsolute ? '/' : '';
     while (path.toString() != terminator) {
       var dir = new Directory.fromPath(path);
       if (dir.existsSync()) break;
       dirsToCreate.add(dir);
       path = path.directoryPath;
     }
     for (var i = dirsToCreate.length - 1; i >= 0; i--) {
       dirsToCreate[i].createSync();
@@ skipping 261 matching lines @@
       controller.addError(
           new DirectoryException("Directory listing failed",
                                  errorPath,
                                  err));
     } else {
       controller.addError(
           new DirectoryException("Internal error"));
     }
   }
 }