Making all DOM types abstract and removing superfluous Dartium constructors.

tools/dom/templates/html/impl/impl_HTMLInputElement.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 $LIBRARYNAME;
 
-$(ANNOTATIONS)class $CLASSNAME$EXTENDS implements
+$(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS implements
     HiddenInputElement,
     SearchInputElement,
     TextInputElement,
     UrlInputElement,
     TelephoneInputElement,
     EmailInputElement,
     PasswordInputElement,
     DateInputElement,
     MonthInputElement,
     WeekInputElement,
@@ skipping 631 matching lines @@
   factory ResetButtonInputElement() => new InputElement(type: 'reset');
 }
 
 /**
  * A button, with no default behavior.
  */
 abstract class ButtonInputElement implements InputElementBase {
   factory ButtonInputElement() => new InputElement(type: 'button');
 }