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

tracing/tracing/ui/tracks/chart_track_test.html

Index: tracing/tracing/ui/tracks/chart_track_test.html
diff --git a/tracing/tracing/ui/tracks/chart_track_test.html b/tracing/tracing/ui/tracks/chart_track_test.html
index 7595a2e2cd75de5e48808b4b79aefc255e91c75e..1671218f667f17f65befdcf8accd4df7de744060 100644
--- a/tracing/tracing/ui/tracks/chart_track_test.html
+++ b/tracing/tracing/ui/tracks/chart_track_test.html
@@ -101,10 +101,10 @@ tr.b.unittest.testSuite(function() {
     var div = document.createElement('div');
     var viewport = new Viewport(div);
     var drawingContainer = new tr.ui.tracks.DrawingContainer(viewport);
-    div.appendChild(drawingContainer);
+    Polymer.dom(div).appendChild(drawingContainer);
 
     var track = buildTrack(viewport);
-    drawingContainer.appendChild(track);
+    Polymer.dom(drawingContainer).appendChild(track);
 
     this.addHTMLOutput(div);
     drawingContainer.invalidate();
@@ -122,10 +122,10 @@ tr.b.unittest.testSuite(function() {
     var viewport = new Viewport(div);
     viewport.highDetails = true;
     var drawingContainer = new tr.ui.tracks.DrawingContainer(viewport);
-    div.appendChild(drawingContainer);
+    Polymer.dom(div).appendChild(drawingContainer);
 
     var track = buildTrack(viewport);
-    drawingContainer.appendChild(track);
+    Polymer.dom(drawingContainer).appendChild(track);
 
     track.series[0].points[1].modelItem.selectionState =
       SelectionState.SELECTED;