Changing template file names to key off of the DOM name rather than Dart name.

sdk/lib/html/templates/html/impl/impl_XMLHttpRequest.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.
 
 part of html;
 
 /// @domName $DOMNAME
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   factory $CLASSNAME.get(String url, onComplete($CLASSNAME request)) =>
       _$(CLASSNAME)FactoryProvider.create$(CLASSNAME)_get(url, onComplete);
 
   factory $CLASSNAME.getWithCredentials(String url,
       onComplete($CLASSNAME request)) =>
       _$(CLASSNAME)FactoryProvider.create$(CLASSNAME)_getWithCredentials(url,
       onComplete);
 
 $!MEMBERS
 }