Revert "First rev of Safe DOM"

pkg/custom_element/test/custom_element_test.dart

Index: pkg/custom_element/test/custom_element_test.dart
diff --git a/pkg/custom_element/test/custom_element_test.dart b/pkg/custom_element/test/custom_element_test.dart
index 341713aa364db6f061643e4c0b43f6a588efa2c2..e2f920a18f2ad1321481e918abe5272fd0d8cc21 100644
--- a/pkg/custom_element/test/custom_element_test.dart
+++ b/pkg/custom_element/test/custom_element_test.dart
@@ -25,8 +25,7 @@ main() {
 customElementTests() {
   test('register creates the element and calls lifecycle methods', () {
     // Add element to the page.
-    var element = new Element.html('<fancy-button>foo bar</fancy-button>',
-        treeSanitizer: new NullTreeSanitizer());
+    var element = new Element.html('<fancy-button>foo bar</fancy-button>');
     document.body.nodes.add(element);
 
     var xtag = null;
@@ -92,10 +91,3 @@ class FancyButton extends CustomElement {
     lifecycle.add('removed');
   }
 }
-
-/**
- * Sanitizer which does nothing.
- */
-class NullTreeSanitizer implements NodeTreeSanitizer {
-  void sanitizeTree(Node node) {}
-}