`new` is not detecting explicitly bound functions

I was running examples from _You Don't Know JS_, and when I plugged this into the live editor, it gave the wrong results:

```
var foo = function(something) {
this.a = something;
};

var obj1 = {};

var bar = foo.bind( obj1 );
bar( 2 );
println( obj1.a ); // expected 2, actual 2

var baz = new bar( 3 );
println( obj1.a ); // expected 2, actual 3
println( baz.a ); // expected 3, actual undefined
```
I confirmed that it normally works by replacing `println` with `console.log`, and running it in the debugger. The debugger gave all the expected values.
Something with `foo.bind` isn't working correctly (which doesn't make sense, because it returns native code), or the `new` constructor isn't accounting for function bindings.

EDIT: added example: https://www.khanacademy.org/computer-programming/_/6379005266198528

Start in the live editor's JavaScript execution path and reproduce the provided example involving foo.bind, bar, and new bar. Trace how bound functions and constructor calls are handled; done means the example prints 2 for obj1.a and 3 for baz.a as shown in the expected results.

Written by the indexing model from the issue text.