[polymer] Switches .appendChild() to Polymer.dom()...appendChild()

tracing/tracing/ui/view_specific_brushing_state_test.html

Index: tracing/tracing/ui/view_specific_brushing_state_test.html
diff --git a/tracing/tracing/ui/view_specific_brushing_state_test.html b/tracing/tracing/ui/view_specific_brushing_state_test.html
index e4e8ece0441f0568913df8292d203dd5fb1ec29b..aff2cc5a4739848b77ddd53fa95d5e53bfeba30d 100644
--- a/tracing/tracing/ui/view_specific_brushing_state_test.html
+++ b/tracing/tracing/ui/view_specific_brushing_state_test.html
@@ -18,13 +18,13 @@ tr.b.unittest.testSuite(function() {
     var stateElement = document.createElement(
         'tr-ui-b-view-specific-brushing-state');
     stateElement.viewId = viewId;
-    containerEl.appendChild(stateElement);
+    Polymer.dom(containerEl).appendChild(stateElement);
     return stateElement;
   }
 
   function addChildDiv(element) {
     var child = element.ownerDocument.createElement('div');
-    element.appendChild(child);
+    Polymer.dom(element).appendChild(child);
     return child;
   }