Revert "Making all DOM types abstract and removing superfluous Dartium constructors."

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

 // Copyright (c) 2011, 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 $LIBRARYNAME;
 
-$(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
+$(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   factory $CLASSNAME() => document.createDocumentFragment();
 
   factory $CLASSNAME.html(String html) {
     final fragment = new DocumentFragment();
     fragment.innerHtml = html;
     return fragment;
   }
 
   factory $CLASSNAME.svg(String svgContent) {
     final fragment = new DocumentFragment();
@@ skipping 64 matching lines @@
   /**
    * Parses the specified text as HTML and adds the resulting node after the
    * last child of this document fragment.
    */
   void appendHtml(String text) {
     this.append(new DocumentFragment.html(text));
   }
 
 $!MEMBERS
 }