Fix union types of variadic functions
Fix union types of variadic functions

The check used `=== len - 1` instead of `>= len - 1` to check whether a
parameter index might be pointing to a rest argument.

jwbay/TypeScript,thr0w/Thr0wScript,ionux/TypeScript,kimamula/TypeScript,thr0w/Thr0wScript,mihailik/TypeScript,weswigham/TypeScript,chuckjaz/TypeScript,nycdotnet/TypeScript,mihailik/TypeScript,mihailik/TypeScript,jwbay/TypeScript,AbubakerB/TypeScript,weswigham/TypeScript,weswigham/TypeScript,kitsonk/TypeScript,basarat/TypeScript,synaptek/TypeScript,donaldpipowitch/TypeScript,ionux/TypeScript,alexeagle/TypeScript,mmoskal/TypeScript,erikmcc/TypeScript,donaldpipowitch/TypeScript,samuelhorwitz/typescript,SaschaNaz/TypeScript,minestarks/TypeScript,yortus/TypeScript,DLehenbauer/TypeScript,evgrud/TypeScript,ziacik/TypeScript,vilic/TypeScript,chuckjaz/TypeScript,evgrud/TypeScript,Eyas/TypeScript,AbubakerB/TypeScript,TukekeSoft/TypeScript,DLehenbauer/TypeScript,TukekeSoft/TypeScript,blakeembrey/TypeScript,RyanCavanaugh/TypeScript,samuelhorwitz/typescript,microsoft/TypeScript,minestarks/TypeScript,nojvek/TypeScript,kpreisser/TypeScript,Eyas/TypeScript,donaldpipowitch/TypeScript,kimamula/TypeScript,plantain-00/TypeScript,RyanCavanaugh/TypeScript,thr0w/Thr0wScript,fabioparra/TypeScript,Microsoft/TypeScript,ionux/TypeScript,mmoskal/TypeScript,synaptek/TypeScript,kitsonk/TypeScript,Microsoft/TypeScript,DLehenbauer/TypeScript,plantain-00/TypeScript,evgrud/TypeScript,samuelhorwitz/typescript,yortus/TypeScript,fabioparra/TypeScript,ziacik/TypeScript,evgrud/TypeScript,kitsonk/TypeScript,erikmcc/TypeScript,synaptek/TypeScript,erikmcc/TypeScript,microsoft/TypeScript,blakeembrey/TypeScript,RyanCavanaugh/TypeScript,alexeagle/TypeScript,synaptek/TypeScript,kpreisser/TypeScript,DLehenbauer/TypeScript,alexeagle/TypeScript,kpreisser/TypeScript,SaschaNaz/TypeScript,fabioparra/TypeScript,mihailik/TypeScript,jeremyepling/TypeScript,chuckjaz/TypeScript,yortus/TypeScript,erikmcc/TypeScript,mmoskal/TypeScript,Eyas/TypeScript,fabioparra/TypeScript,mmoskal/TypeScript,SaschaNaz/TypeScript,ziacik/TypeScript,jeremyepling/TypeScript,nojvek/TypeScript,chuckjaz/TypeScript,blakeembrey/TypeScript,samuelhorwitz/typescript,vilic/TypeScript,nycdotnet/TypeScript,Microsoft/TypeScript,plantain-00/TypeScript,basarat/TypeScript,blakeembrey/TypeScript,ziacik/TypeScript,ionux/TypeScript,yortus/TypeScript,vilic/TypeScript,nojvek/TypeScript,plantain-00/TypeScript,nojvek/TypeScript,AbubakerB/TypeScript,jwbay/TypeScript,Eyas/TypeScript,donaldpipowitch/TypeScript,SaschaNaz/TypeScript,microsoft/TypeScript,vilic/TypeScript,nycdotnet/TypeScript,basarat/TypeScript,thr0w/Thr0wScript,AbubakerB/TypeScript,TukekeSoft/TypeScript,kimamula/TypeScript,jeremyepling/TypeScript,minestarks/TypeScript,kimamula/TypeScript,jwbay/TypeScript,basarat/TypeScript,nycdotnet/TypeScript