Add test cases for function node (#1402)
Add test cases for function node (#1402)

* Add test cases for function node

* Remove test case for keys() in global context

rdrm2014/node-red,rdrm2014/node-red,node-red/node-red,mw75/node-red,mw75/node-red,btsimonh/node-red,node-red/node-red,HiroyasuNishiyama/node-red,mw75/node-red,btsimonh/node-red,rdrm2014/node-red,node-red/node-red,namgk/node-red,HiroyasuNishiyama/node-red,btsimonh/node-red,Kazuki-Nakanishi/node-red,Kazuki-Nakanishi/node-red,namgk/node-red,mw75/node-red,HiroyasuNishiyama/node-red,Kazuki-Nakanishi/node-red,rdrm2014/node-red,Kazuki-Nakanishi/node-red