fix placeholder again

components/datepicker/index.jsx

@@ -13,7 +13,6 @@ function createPicker(TheCalendar) {
     getDefaultProps() {
       return {
         format: 'yyyy-MM-dd',
-        placeholder: '',
         transitionName: 'slide-up',
         popupStyle: {},
         onSelect: null, // 向前兼容
@@ -94,7 +93,8 @@ function createPicker(TheCalendar) {
       let defaultCalendarValue = new GregorianCalendar(this.getLocale());
       defaultCalendarValue.setTime(Date.now());
 
-      const placeholder = this.props.placeholder || this.getLocale().lang.placeholder;
+      const placeholder = ('placeholder' in this.props)
+        ? this.placeholder : this.getLocale().lang.placeholder;
       const calendar = (
         <TheCalendar
           disabledDate={this.props.disabledDate}

components/timepicker/index.jsx

@@ -8,7 +8,6 @@ const AntTimepicker = React.createClass({
   getDefaultProps() {
     return {
       format: 'HH:mm:ss',
-      placeholder: '',
       prefixCls: 'ant-timepicker',
       onChange() {},
       locale: {},
@@ -67,7 +66,8 @@ const AntTimepicker = React.createClass({
   render() {
     const { format } = this.props;
     const formatter = new DateTimeFormat(format);
-    const placeholder = this.props.placeholder || this.getLocale().lang.placeholder;
+    const placeholder = ('placeholder' in this.props)
+      ? this.props.placeholder : this.getLocale().lang.placeholder;
     return (
       <TimePicker
         {...this.props}