don't recalculate style for elements whose class set didn't change
don't recalculate style for elements whose class set didn't change

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