Make Object.assign also copy 3rd and 4th args properties
Make Object.assign also copy 3rd and 4th args properties

Closes ternjs/tern_for_sublime#160

fileability/tern,neoclide/tern,emacsmirror/tern,neoclide/tern,ternjs/tern,neoclide/tern,emacsmirror/tern,marijnh/tern,marijnh/tern,MarcelGerber/tern,fileability/tern,marijnh/tern,ternjs/tern,othree/tern,othree/tern,othree/tern,emacsmirror/tern,MarcelGerber/tern,ternjs/tern,MarcelGerber/tern,fileability/tern