minor bugfix for the element sort function of the renderer
minor bugfix for the element sort function of the renderer

cytoscape/cytoscape.js,soomin-maeng/cytoscape.js,rlugojr/cytoscape.js,cytoscape/cytoscape.js,soomin-maeng/cytoscape.js,KonstantinShemyak/cytoscape.js,rlugojr/cytoscape.js,KonstantinShemyak/cytoscape.js