Revert "Dartium JS Interop enabled."

tools/dom/src/NodeValidatorBuilder.dart

Index: tools/dom/src/NodeValidatorBuilder.dart
diff --git a/tools/dom/src/NodeValidatorBuilder.dart b/tools/dom/src/NodeValidatorBuilder.dart
index f884caeb4420dedfb96cd6550e7cc68c0a7763e5..4a412325bd30ba1bf628e02184d54852f7e7a786 100644
--- a/tools/dom/src/NodeValidatorBuilder.dart
+++ b/tools/dom/src/NodeValidatorBuilder.dart
@@ -358,11 +358,11 @@ class _SimpleNodeValidator implements NodeValidator {
   }
 
   bool allowsElement(Element element) {
-    return allowedElements.contains(element._safeTagName);
+    return allowedElements.contains(element.tagName);
   }
 
   bool allowsAttribute(Element element, String attributeName, String value) {
-    var tagName = element._safeTagName;
+    var tagName = element.tagName;
     if (allowedUriAttributes.contains('$tagName::$attributeName')) {
       return uriPolicy.allowsUri(value);
     } else if (allowedUriAttributes.contains('*::$attributeName')) {
@@ -403,10 +403,10 @@ class _CustomElementNodeValidator extends _SimpleNodeValidator {
       var isAttr = element.attributes['is'];
       if (isAttr != null) {
         return allowedElements.contains(isAttr.toUpperCase()) &&
-          allowedElements.contains(element._safeTagName);
+          allowedElements.contains(element.tagName);
       }
     }
-    return allowCustomTag && allowedElements.contains(element._safeTagName);
+    return allowCustomTag && allowedElements.contains(element.tagName);
   }
 
   bool allowsAttribute(Element element, String attributeName, String value) {
@@ -462,7 +462,7 @@ class _SvgNodeValidator implements NodeValidator {
     // foreignobject tag as SvgElement. We don't want foreignobject contents
     // anyway, so just remove the whole tree outright. And we can't rely
     // on IE recognizing the SvgForeignObject type, so go by tagName. Bug 23144
-    if (element is svg.SvgElement && element._safeTagName == 'foreignObject') {
+    if (element is svg.SvgElement && element.tagName == 'foreignObject') {
       return false;
     }
     if (element is svg.SvgElement) {