IE11 xhr.send(undefined) sends 'undefined' string as POST payload

[davepies]

If Vue.http.post gets called without passing in any data, the body of the request-body will contain a string "undefined".

This is a known quirk of IE11 (see MR on superagent)

Note: This only happens if Object.assign is being polyfilled - not if the internal assign-util is being called.

Reproduction Link

jsfiddle to reproduce

Steps to reproduce

Load the jsfiffle in IE11.

What is Expected?

The request's body should be empty and the data field in the example above should be an empty string.

What is actually happening?

The data field contains a string 'undefined'