Promote DOMType to public dart:dom type.

client/dom/common/public.dart

 // Common declarations.
 
 interface Acceleration {}
 
 interface CompareHow {}
 
 typedef void EventListener(Event event);
 
 interface MediaQueryListListener {}
 
@@ skipping 542 matching lines @@
 }
 
 // FIXME: remove when prefix is working in the VM.
 Window get dom_window() {
   return 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.");
+  }
+}