Move JS calls out of Dartium code

tools/dom/src/Validators.dart

Index: tools/dom/src/Validators.dart
diff --git a/tools/dom/src/Validators.dart b/tools/dom/src/Validators.dart
index d7fd920b79400ada5d947f459469a35dd2f70c49..d964153afea1d46ce71e489f3bd4773977f9dc05 100644
--- a/tools/dom/src/Validators.dart
+++ b/tools/dom/src/Validators.dart
@@ -209,11 +209,12 @@ 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';