test.js

object.forEachMethod = function(fn){
    if (!methodsEnumerable) for (var i = 0, l = methods.length; i < l; i++){
        fn.call(prototype, prototype[methods[i]], methods[i]);
    }
    for (var key in prototype) fn.call(prototype, prototype[key], key)
};

// Listing non-enumerable methods here. But there's no "contains" before
// https://github.com/mootools/mootools-core/commit/521471f5c0617edc12c680cdad8346c3eb95776a
...('Array', Array, [
	'pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift', 'concat', 'join', 'slice',
	'indexOf', 'lastIndexOf', 'filter', 'forEach', 'every', 'map', 'some', 'reduce', 'reduceRight'
    ]) ...

// Now, 'contains' is not enumerated.
Array.forEachMethod(function(method, name){
    Elements.implement(name, method);
});