[polymer] Replaces this.appendChild with Polymer.dom(this).appendChild

tracing/tracing/ui/extras/chrome/cc/picture_ops_chart_view.html

Index: tracing/tracing/ui/extras/chrome/cc/picture_ops_chart_view.html
diff --git a/tracing/tracing/ui/extras/chrome/cc/picture_ops_chart_view.html b/tracing/tracing/ui/extras/chrome/cc/picture_ops_chart_view.html
index a62f128e6b93221284e402e09c1c224d1e16f6ca..e1d537f2e9aed2515f0905b1da0185b0041f80e5 100644
--- a/tracing/tracing/ui/extras/chrome/cc/picture_ops_chart_view.html
+++ b/tracing/tracing/ui/extras/chrome/cc/picture_ops_chart_view.html
@@ -49,7 +49,7 @@ tr.exportTo('tr.ui.e.chrome.cc', function() {
 
       this.chart_ = document.createElement('canvas');
       this.chartCtx_ = this.chart_.getContext('2d');
-      this.appendChild(this.chart_);
+      Polymer.dom(this).appendChild(this.chart_);
 
       this.selectedOpIndex_ = undefined;
       this.chartWidth_ = 0;
@@ -70,7 +70,7 @@ tr.exportTo('tr.ui.e.chrome.cc', function() {
           'PictureOpsChartView.usePercentileScale', false,
           'Limit to 95%-ile');
       this.usePercentileScaleCheckbox_.classList.add('use-percentile-scale');
-      this.appendChild(this.usePercentileScaleCheckbox_);
+      Polymer.dom(this).appendChild(this.usePercentileScaleCheckbox_);
     },
 
     get dimensionsHaveChanged() {