Revert "User `files` in package.json"
Revert "User `files` in package.json"

This reverts commit 263b4f79cb202040cd2c14af6dbeae9b90c9aa60 from #300.

matthewjh/es5-shim,imsun/es5-shim,meteor/es5-shim,imsun/es5-shim,fashionsun/es5-shim,briandipalma/es5-shim,sky-uk/es5-shim,goodbedford/es5-shim,fashionsun/es5-shim,es-shims/es5-shim,meteor/es5-shim,laomu1988/es5-shim,briandipalma/es5-shim,laomu1988/es5-shim,ljharb/es5-shim,jefferydutra/es5-shim,jefferydutra/es5-shim,olemis/es5-shim,matthewjh/es5-shim,ljharb/es5-shim,9040044/es5-shim,Xotic750/es5-shim,shuaiyunzhang/es5-shim,9040044/es5-shim,sky-uk/es5-shim,lewisje/es5-shim,goodbedford/es5-shim,lewisje/es5-shim,es-shims/es5-shim,shuaiyunzhang/es5-shim,olemis/es5-shim,Xotic750/es5-shim