DevTools: fix private field usage violation discovered after the compiler roll.

third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 143 matching lines @@
    */
   setLayers(payload, callback) {
     if (!payload) {
       onBackendNodeIdsResolved.call(this);
       return;
     }
 
     var idsToResolve = new Set();
     for (var i = 0; i < payload.length; ++i) {
       var backendNodeId = payload[i].backendNodeId;
-      if (!backendNodeId || this._backendNodeIdToNode.has(backendNodeId))
+      if (!backendNodeId || this.backendNodeIdToNode().has(backendNodeId))
         continue;
       idsToResolve.add(backendNodeId);
     }
-    this._resolveBackendNodeIds(idsToResolve, onBackendNodeIdsResolved.bind(this));
+    this.resolveBackendNodeIds(idsToResolve, onBackendNodeIdsResolved.bind(this));
 
     /**
      * @this {Layers.AgentLayerTree}
      */
     function onBackendNodeIdsResolved() {
       this._innerSetLayers(payload);
       callback();
     }
   }
 
@@ skipping 12 matching lines @@
     for (var i = 0; i < layers.length; ++i) {
       var layerId = layers[i].layerId;
       var layer = oldLayersById[layerId];
       if (layer)
         layer._reset(layers[i]);
       else
         layer = new Layers.AgentLayer(this._target, layers[i]);
       this._layersById[layerId] = layer;
       var backendNodeId = layers[i].backendNodeId;
       if (backendNodeId)
-        layer._setNode(this._backendNodeIdToNode.get(backendNodeId));
+        layer._setNode(this.backendNodeIdToNode().get(backendNodeId));
       if (!this.contentRoot() && layer.drawsContent())
         this.setContentRoot(layer);
       var parentId = layer.parentId();
       if (parentId) {
         var parent = this._layersById[parentId];
         if (!parent)
           console.assert(parent, 'missing parent ' + parentId + ' for layer ' + layerId);
         parent.addChild(layer);
       } else {
         if (root)
@@ skipping 348 matching lines @@
 
   /**
    * @override
    * @param {!Protocol.LayerTree.LayerId} layerId
    * @param {!Protocol.DOM.Rect} clipRect
    */
   layerPainted(layerId, clipRect) {
     this._layerTreeModel._layerPainted(layerId, clipRect);
   }
 };