iOS唤起input慢

在JS中添加如下代码即可：

FastClick.attach(document.body); //300ms延迟
//init
/**
  * @param {EventTarget|Element} targetElement
  */
FastClick.prototype.focus = function (targetElement) {
    var length;

    // Issue #160: on iOS 7, some input elements (e.g. date datetime month) throw a vague TypeError on setSelectionRange. These elements don't have an integer value for the selectionStart and selectionEnd properties, but unfortunately that can't be used for detection because accessing the properties also throws a TypeError. Just check the type instead. Filed as Apple bug #15122724.
    if (deviceIsIOS && targetElement.setSelectionRange && targetElement.type.indexOf('date') !== 0 && targetElement.type !== 'time' && targetElement.type !== 'month' && targetElement.type !== 'email') {
        length = targetElement.value.length;
        targetElement.focus();//加入这一句话就OK了
        targetElement.setSelectionRange(length, length);
    } else {
        targetElement.focus();
    }
};