babel: 'this' becomes 'undefined' in es2015 preset

Bug: when using this at the global level of your js code, using the es2015 or env preset, it will be transformed to undefined, which is not correct.

Input Code

(function($) {
  // ...
}(this.jQuery));

Output

"use strict";

(function ($) {
  // ...
})(undefined.jQuery);

Babel Configuration

Calling babel via gulp:

.pipe(babel({
    presets: [ "env" ]
}))

No config file otherwise.

Expected Behavior

this should not be transformed into undefined. There is no reason to.

Current Behavior

this at the global context is transformed into undefined.

Possible Solution

It works fine in the es2017 preset, so perhaps copy over what that preset is doing, into es2015.

Context

I’m trying to transform modern javascript into javascript that oldIE can understand, and the above code is how we write our top-level IIFE to avoid conflicts in the global context. this in the global context means the window object.

Your Environment

software	version(s)
Babel	6.26.0
Babel-preset-env	1.6.1
Babel-preset-es2015	6.24.1
Gulp-babel	7.0.1
node	8.10.0
npm	5.7.1
Operating System	Windows 10

Noet: the issue can also be reproduced on the Try it out thing.