Making almost all dom_ methods private. Exceptions will be addressed in a later CL.

tools/dom/templates/html/impl/impl_CustomEvent.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 // WARNING: Do not edit - generated code.
 
 part of $LIBRARYNAME;
 
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   factory $CLASSNAME(String type,
       {bool canBubble: true, bool cancelable: true, Object detail}) {
 
-    final CustomEvent e = document.$dom_createEvent('CustomEvent');
+    final CustomEvent e = document._createEvent('CustomEvent');
 
 $if DART2JS
     detail = convertDartToNative_SerializedScriptValue(detail);
 $endif
-    e.$dom_initCustomEvent(type, canBubble, cancelable, detail);
+    e._initCustomEvent(type, canBubble, cancelable, detail);
 
     return e;
   }
 $!MEMBERS
 }