Move JS calls out of Dartium code

tools/dom/src/Validators.dart

 // Copyright (c) 2013, 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 dart.dom.html;
 
 
 /**
  * Interface used to validate that only accepted elements and attributes are
  * allowed while parsing HTML strings into DOM nodes.
@@ skipping 191 matching lines @@
     // allowing embeds seems quite unlikely. This is also the reason that we
     // can't declare the type of element, as an embed won't pass any type
     // check in dart2js.
     var corrupted = true;
     var attrs;
     var isAttr;
     try {
       // If getting/indexing attributes throws, count that as corrupt.
       attrs = element.attributes;
       isAttr = attrs['is'];
+      var corruptedTest1 = Element._hasCorruptedAttributes(element);
+
       // On IE, erratically, the hasCorruptedAttributes test can return false,
       // even though it clearly is corrupted. A separate copy of the test
       // inlining just the basic check seems to help.
-      var corruptedTest1 = Element._hasCorruptedAttributes(element);
-      var corruptedTest2 = JS('bool', r'!(#.attributes instanceof NamedNodeMap)', element);
+      var corruptedTest2 = Element._hasCorruptedAttributesAdditionalCheck(element);
       corrupted = corruptedTest1 || corruptedTest2;
     } catch(e) {}
     var elementText = 'element unprintable';
     try {
       elementText = element.toString();
     } catch(e) {}
     try {
       var elementTagName = Element._safeTagName(element);
       _sanitizeElement(element, parent, corrupted, elementText, elementTagName,
           attrs, isAttr);
@@ skipping 60 matching lines @@
       case Node.COMMENT_NODE:
       case Node.DOCUMENT_FRAGMENT_NODE:
       case Node.TEXT_NODE:
       case Node.CDATA_SECTION_NODE:
         break;
       default:
         _removeNode(node, parent);
     }
   }
 }