feat(badge): badge support aria

fix Tencent#1019

src/badge/badge.wxml

@@ -1,15 +1,23 @@
 <wxs src="./badge.wxs" module="this" />
 
-<view style="{{ customStyle }}" class="{{this.getBadgeOuterClass({shape})}} {{prefix}}-class">
-  <view class="{{classPrefix}}__content {{prefix}}-class-content">
+<view
+  style="{{ customStyle }}"
+  class="{{this.getBadgeOuterClass({shape})}} {{prefix}}-class"
+  aria-labelledby="labelledby"
+  aria-describedby="describedby"
+  aria-role="{{ ariaRole || 'option'}}"
+>
+  <view id="labelledby" class="{{classPrefix}}__content {{prefix}}-class-content">
     <slot wx:if="{{!content}}" class="{{classPrefix}}__content-slot" />
     <text wx:else class="{{classPrefix}}__content-text">{{content}}</text>
   </view>
   <view
+    aria-label="{{ this.getBadgeAriaLabel({dot, count, maxCount}) }}"
+    id="describedby"
     wx:if="{{count !== 'slot' && this.isShowBadge({dot,count,showZero})}}"
     class="{{this.getBadgeInnerClass({dot, size, shape, count})}} {{prefix}}-has-count {{prefix}}-class-count"
     style="{{this.getBadgeStyles({color, offset})}}"
     >{{ this.getBadgeValue({dot, count, maxCount}) }}
   </view>
-  <slot name="count" wx:if="{{count === 'slot' || !count}}" />
+  <slot id="describedby" name="count" wx:if="{{count === 'slot' || !count}}" />
 </view>

src/badge/badge.wxs

@@ -63,8 +63,22 @@ var isShowBadge = function (props) {
   return true;
 };
 
+var getBadgeAriaLabel = function (props) {
+  if (props.dot) {
+    return '有新的消息';
+  }
+  if (isNaN(props.count) || isNaN(props.maxCount)) {
+    var str = '有' + props.count + '通知';
+    return str;
+  }
+  var str1 = '有' + props.maxCount + '+个消息';
+  var str2 = '有' + props.count + '个消息';
+  return parseInt(props.count) > props.maxCount ? str1 : str2;
+};
+
 module.exports.getBadgeValue = getBadgeValue;
 module.exports.getBadgeStyles = getBadgeStyles;
 module.exports.getBadgeOuterClass = getBadgeOuterClass;
 module.exports.getBadgeInnerClass = getBadgeInnerClass;
+module.exports.getBadgeAriaLabel = getBadgeAriaLabel;
 module.exports.isShowBadge = isShowBadge;