Vue源码中关于拦截数组方法的困惑?

// Vue 2.0 src/core/observer/array.js

;[
    'push',
    'pop',
    'shift',
    'unshift',
    'splice',
    'sort',
    'reverse'
]
    .forEach(function (method) {
        // cache original method
        const original = arrayProto[method]
        def(arrayMethods, method, function mutator() {
            // avoid leaking arguments:
            // http://jsperf.com/closure-with-arguments(失效)
            let i = arguments.length
            const args = new Array(i)
            while (i--) {
                args[i] = arguments[i]
            }
            const result = original.apply(this, args)

注释中说避免泄露参数。不明白如果不按源码中那么写，是如何有泄露参数的风险?