Promote DOMType to public dart:dom type.

client/dom/common/implementation.dart

Index: client/dom/common/implementation.dart
diff --git a/client/dom/common/implementation.dart b/client/dom/common/implementation.dart
index 1b92e6abf3362394eb03024e437e79d81fbbde1a..137ebdf481b08963a34a4aa2b7a8097681d16f2a 100644
--- a/client/dom/common/implementation.dart
+++ b/client/dom/common/implementation.dart
@@ -1,12 +1,3 @@
-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.");
-  }
-}
-
 class ListBase<E> extends DOMType implements List<E> {
   ListBase();