Promote DOMType to public dart:dom type.

client/dom/common/public.dart

Index: client/dom/common/public.dart
diff --git a/client/dom/common/public.dart b/client/dom/common/public.dart
index 9b5ea4fcc9f126ead047acf09bdd37a68feb8dc4..8ee58ca82b8a3889dfe2dd99b271e402cbc6804e 100644
--- a/client/dom/common/public.dart
+++ b/client/dom/common/public.dart
@@ -560,3 +560,12 @@ Window get dom_window() {
 Document get document() {
   return window.document;
 }
+
+class DOMType extends DOMWrapperBase {
+  // FIXME: Remove if/when Dart supports OLS for all objects.
+  var dartObjectLocalStorage;
+
+  String get typeName() {
+    throw new UnsupportedOperationException("typeName must be overridden.");
+  }
+}