Compile reactive-dict with ecmascript for IE8
Compile reactive-dict with ecmascript for IE8

We were using `delete` as a key, which IE8 didn't like.

Fixes #5484

4commerce-technologies-AG/meteor,lpinto93/meteor,meteor-velocity/meteor,DAB0mB/meteor,lpinto93/meteor,EduShareOntario/meteor,4commerce-technologies-AG/meteor,Hansoft/meteor,Quicksteve/meteor,nuvipannu/meteor,nuvipannu/meteor,meonkeys/meteor,mjmasn/meteor,AnthonyAstige/meteor,EduShareOntario/meteor,benstoltz/meteor,yonas/meteor-freebsd,AnthonyAstige/meteor,Urigo/meteor,lorensr/meteor,benstoltz/meteor,devgrok/meteor,lpinto93/meteor,DAB0mB/meteor,Hansoft/meteor,benstoltz/meteor,4commerce-technologies-AG/meteor,benstoltz/meteor,aldeed/meteor,Quicksteve/meteor,mjmasn/meteor,newswim/meteor,aldeed/meteor,aldeed/meteor,Quicksteve/meteor,4commerce-technologies-AG/meteor,newswim/meteor,Quicksteve/meteor,jdivy/meteor,nuvipannu/meteor,meteor-velocity/meteor,nuvipannu/meteor,Hansoft/meteor,chasertech/meteor,yonas/meteor-freebsd,benstoltz/meteor,yonas/meteor-freebsd,devgrok/meteor,lorensr/meteor,jdivy/meteor,meteor-velocity/meteor,yonas/meteor-freebsd,Urigo/meteor,EduShareOntario/meteor,mjmasn/meteor,yonas/meteor-freebsd,devgrok/meteor,AnthonyAstige/meteor,DAB0mB/meteor,jdivy/meteor,jdivy/meteor,lassombra/meteor,shrop/meteor,mjmasn/meteor,newswim/meteor,Hansoft/meteor,yonas/meteor-freebsd,chasertech/meteor,meonkeys/meteor,Urigo/meteor,chasertech/meteor,EduShareOntario/meteor,lorensr/meteor,Quicksteve/meteor,lassombra/meteor,shrop/meteor,mjmasn/meteor,shrop/meteor,DAB0mB/meteor,lassombra/meteor,meonkeys/meteor,lorensr/meteor,Hansoft/meteor,jdivy/meteor,aldeed/meteor,AnthonyAstige/meteor,lorensr/meteor,lorensr/meteor,DAB0mB/meteor,jdivy/meteor,nuvipannu/meteor,DAB0mB/meteor,Hansoft/meteor,shrop/meteor,aldeed/meteor,meonkeys/meteor,4commerce-technologies-AG/meteor,mjmasn/meteor,newswim/meteor,4commerce-technologies-AG/meteor,EduShareOntario/meteor,lpinto93/meteor,meteor-velocity/meteor,Quicksteve/meteor,lassombra/meteor,AnthonyAstige/meteor,meteor-velocity/meteor,lpinto93/meteor,lpinto93/meteor,devgrok/meteor,devgrok/meteor,AnthonyAstige/meteor,4commerce-technologies-AG/meteor,EduShareOntario/meteor,nuvipannu/meteor,nuvipannu/meteor,benstoltz/meteor,lassombra/meteor,DAB0mB/meteor,aldeed/meteor,benstoltz/meteor,shrop/meteor,jdivy/meteor,AnthonyAstige/meteor,devgrok/meteor,shrop/meteor,lorensr/meteor,meonkeys/meteor,newswim/meteor,mjmasn/meteor,Urigo/meteor,newswim/meteor,lpinto93/meteor,chasertech/meteor,newswim/meteor,lassombra/meteor,Urigo/meteor,chasertech/meteor,EduShareOntario/meteor,meteor-velocity/meteor,chasertech/meteor,Hansoft/meteor,meteor-velocity/meteor,chasertech/meteor,yonas/meteor-freebsd,Urigo/meteor,meonkeys/meteor,aldeed/meteor,Urigo/meteor,meonkeys/meteor,lassombra/meteor,devgrok/meteor,shrop/meteor,Quicksteve/meteor,AnthonyAstige/meteor