[JENKINS-11618] Adding back the 'toJSON' instance method.
[JENKINS-11618] Adding back the 'toJSON' instance method.

This change, in parallel to a fix in stapler bind.js, would maximize the
backward compatibility.

sathiya-mit/jenkins,recena/jenkins,Vlatombe/jenkins,DanielWeber/jenkins,andresrc/jenkins,rsandell/jenkins,v1v/jenkins,viqueen/jenkins,godfath3r/jenkins,pjanouse/jenkins,aldaris/jenkins,ikedam/jenkins,Vlatombe/jenkins,rsandell/jenkins,MarkEWaite/jenkins,damianszczepanik/jenkins,MarkEWaite/jenkins,pjanouse/jenkins,daniel-beck/jenkins,amuniz/jenkins,andresrc/jenkins,viqueen/jenkins,Jochen-A-Fuerbacher/jenkins,rsandell/jenkins,bkmeneguello/jenkins,recena/jenkins,oleg-nenashev/jenkins,ikedam/jenkins,aldaris/jenkins,Vlatombe/jenkins,oleg-nenashev/jenkins,bkmeneguello/jenkins,Vlatombe/jenkins,patbos/jenkins,recena/jenkins,stephenc/jenkins,godfath3r/jenkins,kohsuke/hudson,oleg-nenashev/jenkins,patbos/jenkins,aldaris/jenkins,pjanouse/jenkins,godfath3r/jenkins,MarkEWaite/jenkins,godfath3r/jenkins,Jochen-A-Fuerbacher/jenkins,amuniz/jenkins,godfath3r/jenkins,rsandell/jenkins,batmat/jenkins,ikedam/jenkins,MarkEWaite/jenkins,daniel-beck/jenkins,MarkEWaite/jenkins,stephenc/jenkins,aldaris/jenkins,v1v/jenkins,aldaris/jenkins,DanielWeber/jenkins,DanielWeber/jenkins,amuniz/jenkins,v1v/jenkins,bkmeneguello/jenkins,kohsuke/hudson,viqueen/jenkins,oleg-nenashev/jenkins,oleg-nenashev/jenkins,stephenc/jenkins,pjanouse/jenkins,kohsuke/hudson,sathiya-mit/jenkins,recena/jenkins,amuniz/jenkins,v1v/jenkins,sathiya-mit/jenkins,jenkinsci/jenkins,v1v/jenkins,patbos/jenkins,bkmeneguello/jenkins,jenkinsci/jenkins,recena/jenkins,recena/jenkins,bkmeneguello/jenkins,Vlatombe/jenkins,daniel-beck/jenkins,andresrc/jenkins,Jochen-A-Fuerbacher/jenkins,batmat/jenkins,Vlatombe/jenkins,jenkinsci/jenkins,stephenc/jenkins,MarkEWaite/jenkins,daniel-beck/jenkins,damianszczepanik/jenkins,patbos/jenkins,sathiya-mit/jenkins,daniel-beck/jenkins,Jochen-A-Fuerbacher/jenkins,v1v/jenkins,batmat/jenkins,jenkinsci/jenkins,kohsuke/hudson,oleg-nenashev/jenkins,damianszczepanik/jenkins,Jochen-A-Fuerbacher/jenkins,batmat/jenkins,stephenc/jenkins,MarkEWaite/jenkins,batmat/jenkins,daniel-beck/jenkins,bkmeneguello/jenkins,jenkinsci/jenkins,sathiya-mit/jenkins,rsandell/jenkins,oleg-nenashev/jenkins,Vlatombe/jenkins,viqueen/jenkins,stephenc/jenkins,Jochen-A-Fuerbacher/jenkins,amuniz/jenkins,damianszczepanik/jenkins,rsandell/jenkins,andresrc/jenkins,daniel-beck/jenkins,recena/jenkins,ikedam/jenkins,amuniz/jenkins,MarkEWaite/jenkins,batmat/jenkins,ikedam/jenkins,Jochen-A-Fuerbacher/jenkins,pjanouse/jenkins,stephenc/jenkins,viqueen/jenkins,damianszczepanik/jenkins,ikedam/jenkins,damianszczepanik/jenkins,patbos/jenkins,patbos/jenkins,jenkinsci/jenkins,viqueen/jenkins,viqueen/jenkins,damianszczepanik/jenkins,kohsuke/hudson,pjanouse/jenkins,kohsuke/hudson,andresrc/jenkins,rsandell/jenkins,kohsuke/hudson,godfath3r/jenkins,andresrc/jenkins,damianszczepanik/jenkins,bkmeneguello/jenkins,jenkinsci/jenkins,DanielWeber/jenkins,kohsuke/hudson,patbos/jenkins,DanielWeber/jenkins,daniel-beck/jenkins,ikedam/jenkins,amuniz/jenkins,pjanouse/jenkins,batmat/jenkins,aldaris/jenkins,aldaris/jenkins,jenkinsci/jenkins,andresrc/jenkins,godfath3r/jenkins,v1v/jenkins,rsandell/jenkins,sathiya-mit/jenkins,DanielWeber/jenkins,DanielWeber/jenkins,ikedam/jenkins,sathiya-mit/jenkins