Chai 4.3.x or higher doesn't run on IE 11

[lnewson]

Chai 4.3 introduced a regression via #1334 that causes chai to throw a syntax error on IE 11. This is because it's using an arrow function here which isn't supported on IE 11.

This is also causing the automated saucelab tests setup for Chai to fail: https://app.saucelabs.com/tests/2e7d344d051d40a9b1524d6df4b86a1b

[Trott]

If I'm not mistaken, the cited commit only appears in Chai 4.3.1. In my tests, 4.3.0 worked for IE 11 but 4.3.1 does not. So perhaps the title of the issue should say 4.3.1 rather than 4.3.x`.

[rbruckheimer]

There was identified an inconsistency between what's in GitHub in 4.3.0 and what's on npm. npm had some changes from master in it, possibly this arrow function as well.

[keithamus]

Fixed in 4.3.2.

Thanks everyone!