Remove the Path class from dart:io

sdk/lib/io/file_impl.dart

Index: sdk/lib/io/file_impl.dart
diff --git a/sdk/lib/io/file_impl.dart b/sdk/lib/io/file_impl.dart
index cf9a7ef36179b5877236b773741b38dd5ca3ca19..f621360746aa2dc845a288b0c6c6269447345fcf 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -246,9 +246,6 @@ class _File implements File {
     }
   }
 
-  // Constructor from Path for file.
-  _File.fromPath(Path path) : this(path.toNativePath());
-
   Future<bool> exists() {
     _ensureFileService();
     List request = new List(2);
@@ -346,8 +343,8 @@ class _File implements File {
   }
 
   Directory get directory {
-    Path path = new Path(this.path).directoryPath;
-    return new Directory.fromPath(path);
+    _Path path = new _Path(this.path).directoryPath;
+    return new Directory(path.toNativePath());
   }
 
   Future<RandomAccessFile> open({FileMode mode: FileMode.READ}) {