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

tracing/tracing/ui/tracks/counter_track_test.html

Index: tracing/tracing/ui/tracks/counter_track_test.html
diff --git a/tracing/tracing/ui/tracks/counter_track_test.html b/tracing/tracing/ui/tracks/counter_track_test.html
index 0c78f1dee2a35f9a903cfbaa217bea82971ea335..a462880222dee84a8bf1e0502802be198c34cf2c 100644
--- a/tracing/tracing/ui/tracks/counter_track_test.html
+++ b/tracing/tracing/ui/tracks/counter_track_test.html
@@ -40,10 +40,10 @@ tr.b.unittest.testSuite(function() {
     var viewport = new Viewport(testEl);
 
     var drawingContainer = new tr.ui.tracks.DrawingContainer(viewport);
-    testEl.appendChild(drawingContainer);
+    Polymer.dom(testEl).appendChild(drawingContainer);
 
     var track = new CounterTrack(viewport);
-    drawingContainer.appendChild(track);
+    Polymer.dom(drawingContainer).appendChild(track);
     this.addHTMLOutput(testEl);
 
     // Force the container to update sizes so the test can use coordinates that
@@ -87,10 +87,10 @@ tr.b.unittest.testSuite(function() {
     var viewport = new Viewport(div);
 
     var drawingContainer = new tr.ui.tracks.DrawingContainer(viewport);
-    div.appendChild(drawingContainer);
+    Polymer.dom(div).appendChild(drawingContainer);
 
     var track = new CounterTrack(viewport);
-    drawingContainer.appendChild(track);
+    Polymer.dom(drawingContainer).appendChild(track);
 
     this.addHTMLOutput(div);
     drawingContainer.invalidate();