Fixing issue #3982.

Refers to https://github.com/zurb/foundation/issues/3982.

"Not a valid argument for 'Function.prototype.apply' JS error in foundation.js (F5) on older Safari"

This error was being thrown in JS on an older iPhone 4 with Safari 5.0.5 and user prembo has indicated that this is also happening on a desktop client with Safari 5.0.5.

I've been able to confirm on a desktop with FF and Chrome this fix doesn't not result in any new errors. Also tested on an iPhone 5 with iOS5 and Android 4.1.