Tell uglifyjs to not mangle undefined; saves 44 bytes. Fixes #13759. Close gh-1239.
Tell uglifyjs to not mangle undefined; saves 44 bytes. Fixes #13759. Close gh-1239.

eburgos/jquery,Karyotyper/jquery,chitranshi/jquery,jcutrell/jquery,jquery/jquery,Karyotyper/jquery,roytoo/jquery,rwaldron/jquery,roytoo/jquery,jquery/jquery,jcutrell/jquery,eburgos/jquery,quiaro/request-agent,demetr84/Jquery,Karyotyper/jquery,chitranshi/jquery,eburgos/jquery,demetr84/Jquery,jquery/jquery,roytoo/jquery,rwaldron/jquery