adds Function.prototype.name polyfill

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-name
It's here: https://people.mozilla.org/~jorendorff/es6-draft.html#sec-variable-statement-runtime-semantics-evaluation

Look under _VariableDeclaration_ : _BindingIdentifier_ _Initializer_, step 4.c.i

This is the original proposal: http://wiki.ecmascript.org/doku.php?id=harmony:function_name_property, I've only linked to it because it has examples that illustrate the expected values.