Remove `uncurryThis` via Function.bind.bind(Function.call).

Not sure in which theory the `Function.bind.bind(Function.call)` variation should be faster. `Function.bind` is native but does much more then what you really need here.
I tested it extensively a few weeks ago with prefjs.com, and it is 2-5 times slower on Firefox and Chrome.

EDIT: I have to correct myself. It is not slower (only) because of `Function.bind`, but (also) because it is done twice.