This code breaks Function.prototype.name in 100% of cases

var funcNameBeforeProtoCall = (function bar() {}).name
var funcNameBeforeProtoCallEquals = funcNameBeforeProtoCall === 'bar';
debugger;
Function.prototype.name;
var funcNameAfterProtoCall = (function foo() {}).name
var funcNameAfterProtoCallEquals = funcNameAfterProtoCall === 'foo';
debugger

launchable code: https://codepen.io/ColCh/pen/Oqpqqp

Try it in IE 11 and this would be resulted in this:

WHY ?!

Because this code is executed against this variable of Function.prototype

and this code assigns getter with for Function.prototype name property with null value.

Solution: skip defineProperty for null names