Linking the built-in Function.call() could be made clever, as it could immediately link to the function being called.

fn.call(this, args...) ends up being a dyn:call(Function.call, fn, this, args...). It could be linked just as dyn:call(fn, this, args...) is; it'd just need to drop the first argument, and use a guard checking if the original two arguments are indeed Function.call and fn.