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

tracing/tracing/ui/timeline_view_test.html

Index: tracing/tracing/ui/timeline_view_test.html
diff --git a/tracing/tracing/ui/timeline_view_test.html b/tracing/tracing/ui/timeline_view_test.html
index e3e2e0609851d4514dbcead7b56a59125973c903..9a5f0fa83b93877a20fc4f7f947ad3e56e38b0e2 100644
--- a/tracing/tracing/ui/timeline_view_test.html
+++ b/tracing/tracing/ui/timeline_view_test.html
@@ -22,7 +22,7 @@ tr.b.unittest.testSuite(function() {
     container.id = 'track_view_container';
 
     var view = document.createElement('tr-ui-timeline-view');
-    view.appendChild(container);
+    Polymer.dom(view).appendChild(container);
     view.trackViewContainer_ = container;
     return view;
   }
@@ -112,11 +112,11 @@ tr.b.unittest.testSuite(function() {
 
     var simpleButton1 = document.createElement('tr-ui-b-toolbar-button');
     simpleButton1.textContent = 'M';
-    view.leftControls.appendChild(simpleButton1);
+    Polymer.dom(view.leftControls).appendChild(simpleButton1);
 
     var simpleButton2 = document.createElement('tr-ui-b-toolbar-button');
     simpleButton2.textContent = 'am button';
-    view.leftControls.appendChild(simpleButton2);
+    Polymer.dom(view.leftControls).appendChild(simpleButton2);
 
     this.addHTMLOutput(view);
   });