Fix some analyzer warnings in dart:io.

sdk/lib/io/directory_impl.dart

Index: sdk/lib/io/directory_impl.dart
diff --git a/sdk/lib/io/directory_impl.dart b/sdk/lib/io/directory_impl.dart
index 17d67bee76cee57bb7f9ca72869ab58112290ad5..e27b6103f64f5ed26756ffce7092598accb0a157 100644
--- a/sdk/lib/io/directory_impl.dart
+++ b/sdk/lib/io/directory_impl.dart
@@ -98,7 +98,7 @@ class _Directory implements Directory {
   }
 
   Future<Directory> createRecursively() {
-    var path = new Path(path);
+    var path = new Path(this.path);
     var dirsToCreate = [];
     var terminator = path.isAbsolute ? '/' : '';
     while (path.toString() != terminator) {
@@ -139,7 +139,7 @@ class _Directory implements Directory {
   }
 
   void createRecursivelySync() {
-    var path = new Path(path);
+    var path = new Path(this.path);
     var dirsToCreate = [];
     var terminator = path.isAbsolute ? '/' : '';
     while (path.toString() != terminator) {