Move JS calls out of Dartium code

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 5cc47e4fca2bbf4ddc19ecbbf5cafb9bb0f7db65..efdef92d354ce5d45f48a5b42352dc03fc95eaae 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -14778,6 +14778,9 @@ class Element extends Node implements GlobalEventHandlers, ParentNode, ChildNode
     return false;
   }
 
+  /// A secondary check for corruption, needed on IE
+  static bool _hasCorruptedAttributesAdditionalCheck(Element element) => false;
+
   static String _safeTagName(element) {
     String result = 'element tag unavailable';
     try {
@@ -46844,11 +46847,12 @@ class _ValidatingTreeSanitizer implements NodeTreeSanitizer {
       // 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';