goog.bindJs_ breaks the length property of resulting function

[GoogleCodeExporter]

What steps will reproduce the problem?
1. bind this/some arguments to a function using goog.bind on a browser that 
does not natively support Function.bind

What is the expected output? What do you see instead?
> var f = function(a,b,c) {};
> f.length === 3
  true
> goog.bind(f, null, 'foo').length

expected: 2
actual: 0

Original issue reported on code.google.com by robert.s...@gmail.com on 16 Jan 2013 at 9:53