jshint fixes for bench/bench.js
jshint fixes for bench/bench.js

rwl/dagre,GerHobbelt/dagre,abduld/dagre,kdawes/dagre,lmcorbo/dagre,tylingsoft/dagre-layout,lmcorbo/dagre,abduld/dagre,tylingsoft/dagre-layout,GerHobbelt/dagre,abduld/dagre,shelsonjava/dagre,9n/dagre,9n/dagre,kdawes/dagre,witcxc/dagre,shelsonjava/dagre,lmcorbo/dagre,9n/dagre,GerHobbelt/dagre,kdawes/dagre,cpettitt/dagre,cpettitt/dagre,shelsonjava/dagre,cpettitt/dagre,witcxc/dagre