Add File.renameSync() to virtual file system.

pkg/analyzer/lib/file_system/physical_file_system.dart

Index: pkg/analyzer/lib/file_system/physical_file_system.dart
diff --git a/pkg/analyzer/lib/file_system/physical_file_system.dart b/pkg/analyzer/lib/file_system/physical_file_system.dart
index 1a4e7939296aba1a74a535b01c0e8dc4008f6bc3..66125a69fa7c53ecbf54d95e10ff4d31d007ddbe 100644
--- a/pkg/analyzer/lib/file_system/physical_file_system.dart
+++ b/pkg/analyzer/lib/file_system/physical_file_system.dart
@@ -140,6 +140,17 @@ class _PhysicalFile extends _PhysicalResource implements File {
       throw new FileSystemException(exception.path, exception.message);
     }
   }
+
+  @override
+  Resource renameSync(String newPath) {
+    try {
+      io.File file = _entry as io.File;
+      io.File newFile = file.renameSync(newPath);
+      return new _PhysicalFile(newFile);
+    } on io.FileSystemException catch (exception) {
+      throw new FileSystemException(exception.path, exception.message);
+    }
+  }
 }
 
 /**