code: function()
      {
          if (!this._savedChildren)
              return;
  
          this.selfTime = this._savedSelfTime;
          this.totalTime = this._savedTotalTime;
          this.numberOfCalls = this._savedNumberOfCalls;
  
          this.removeChildren();
  
          var children = this._savedChildren;
          var count = children.length;
  
          for (var index = 0; index < count; ++index) {
              children[index]._restore();
              this.appendChild(children[index]);
          }
      }
docs: When focusing and collapsing we modify lots of nodes in the tree. This allows us to restore them all to their original state when we revert.