Merge pull request #4 from DamonAmber/patch-1

修复mp-tabbar中，未设置badge值却依旧显示红点的问题

Author: synclife

src/tabbar/tabbar.wxml

@@ -3,7 +3,7 @@
     <view data-index='{{index}}' bindtap="tabChange" wx:for="{{list}}" class="weui-tabbar__item {{index === current ? 'weui-bar__item_on' : ''}}">
         <view style="position: relative;display:inline-block;">
           <image src="{{current === index ? item.selectedIconPath : item.iconPath}}" class="weui-tabbar__icon"></image>
-          <mp-badge content="{{item.badge}}" style="position: absolute;top:-2px;left:calc(100% - 3px)"></mp-badge>
+          <mp-badge wx:if="{{item.badge}}" content="{{item.badge}}" style="position: absolute;top:-2px;left:calc(100% - 3px)"></mp-badge>
         </view>
         <view class="weui-tabbar__label">{{item.text}}</view>
     </view>