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

tracing/tracing/value/ui/scalar_span_test.html

Index: tracing/tracing/value/ui/scalar_span_test.html
diff --git a/tracing/tracing/value/ui/scalar_span_test.html b/tracing/tracing/value/ui/scalar_span_test.html
index b380f591f123dc8517e1c90f227e7f7bdf26e508..134c5990c7b81a07677c0021e0404ef942ad3d7b 100644
--- a/tracing/tracing/value/ui/scalar_span_test.html
+++ b/tracing/tracing/value/ui/scalar_span_test.html
@@ -149,9 +149,9 @@ tr.b.unittest.testSuite(function() {
 
     var overall = document.createElement('div');
     overall.style.display = 'flex';
-    overall.appendChild(spanA);
+    Polymer.dom(overall).appendChild(spanA);
     spanB.style.marginLeft = '4px';
-    overall.appendChild(spanB);
+    Polymer.dom(overall).appendChild(spanB);
     this.addHTMLOutput(overall);
   });
 
@@ -182,7 +182,7 @@ tr.b.unittest.testSuite(function() {
       if (percentage !== null)
         span.percentage = percentage;
 
-      div.appendChild(span);
+      Polymer.dom(div).appendChild(span);
 
       var computedStyle = getComputedStyle(span.$.sparkline);
       assert.equal(computedStyle.display, expectedDisplay);