documentcloud/underscore — comment on commit ed4826ca19bafb2b9ec6aba3f34ec7edafc05d40
File: underscore.js line 116
By jdalton:

~~~ js
// IE < 9 makes properties, shadowing non-enumerable ones, non-enumerable too
var forShadowed = !{valueOf:0}.propertyIsEnumerable('valueOf') &&
~~~