code: function updateChildBounds() {
           this.childBounds.pos.set(Infinity, Infinity);
           this.childBounds.resize(-Infinity, -Infinity);
           var childBounds;
  
           for (var i = this.children.length, child; i--, child = this.children[i];) {
             if (child.isRenderable) {
               if (child instanceof me.Container) {
                 childBounds = child.childBounds;
               } else {
                 childBounds = child.getBounds();
               } // TODO : returns an "empty" rect instead of null (e.g. EntityObject)
               // TODO : getBounds should always return something anyway
  
  
               if (childBounds !== null) {
                 this.childBounds.union(childBounds);
               }
             }
           }
  
           return this.childBounds;
         }
docs: resizes the child bounds rectangle, based on children bounds.
  @name updateChildBounds
  @memberOf me.Container.prototype
  @function
  @return {me.Rect} updated child bounds