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

tracing/tracing/ui/annotations/comment_box_annotation_view.html

Index: tracing/tracing/ui/annotations/comment_box_annotation_view.html
diff --git a/tracing/tracing/ui/annotations/comment_box_annotation_view.html b/tracing/tracing/ui/annotations/comment_box_annotation_view.html
index 03eba86146b83b194a63b3cb9692b24d29e2934f..e8be4588586109ef96516da1648f77a8cc43263a 100644
--- a/tracing/tracing/ui/annotations/comment_box_annotation_view.html
+++ b/tracing/tracing/ui/annotations/comment_box_annotation_view.html
@@ -52,7 +52,7 @@ tr.exportTo('tr.ui.annotations', function() {
         this.textArea_.value = this.annotation_.text;
         // Set the z-index so that this is shown on top of canvas.
         this.textArea_.style.zIndex = 1;
-        ctx.canvas.parentNode.appendChild(this.textArea_);
+        Polymer.dom(ctx.canvas.parentNode).appendChild(this.textArea_);
       }
 
       this.textArea_.style.width = this.styleWidth + 'px';