add ignore if not defined for bad browsers like ie; fixes #341
add ignore if not defined for bad browsers like ie; fixes #341

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