Move dart:dom implementation classes to dart:html library.

lib/dom/src/native_DOMWrapperBase.dart

Index: lib/dom/src/native_DOMWrapperBase.dart
diff --git a/lib/dom/src/native_DOMWrapperBase.dart b/lib/dom/src/native_DOMWrapperBase.dart
index cd9ae886710ae7c3f37d8ce479f830c1e0dc4a60..76ce64feb2c8be65476923939c9ad35ab0ce0af4 100644
--- a/lib/dom/src/native_DOMWrapperBase.dart
+++ b/lib/dom/src/native_DOMWrapperBase.dart
@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-class DOMWrapperBase extends NativeFieldWrapperClass1 implements DOMType {
+class _DOMWrapperBase extends NativeFieldWrapperClass1 {
   var dartObjectLocalStorage;
+
+  abstract String get typeName();
 }