fix(TabBar): 修复文字选中颜色无法默认使用 theme-color 的问题

close #1521

Author: smileShirmy

src/tab-bar/index.js

@@ -24,7 +24,7 @@ Component({
     // 文字选中颜色
     textSelectedColor: {
       type: String,
-      value: '#3963bc'
+      value: ''
     },
     // 文字未选中颜色
     textColor: {

src/tab-bar/index.less

@@ -45,3 +45,7 @@
   font-size: 24rpx;
   line-height: 1;
 }
+
+.@{component}__item-text--selected {
+  color: @theme-color;
+}

src/tab-bar/index.wxml

@@ -7,7 +7,7 @@
         <image class="lu-tab-bar__item-image {{selectedIndex===index?'lu-tab-bar__item-image--selected':''}}" src="{{selectedIndex===index?item.selectedIconPath:item.iconPath}}"></image>
       </l-badge>
       <!-- 标签文字 -->
-      <view wx:if="{{item.text!==undefined}}" class="lu-tab-bar__item-text {{selectedIndex===index?'lu-tab-bar__item-text--selected':''}}" style="color:{{selectedIndex===index?textSelectedColor:textColor}}">
+      <view wx:if="{{item.text!==undefined}}" class="lu-tab-bar__item-text {{selectedIndex===index?'lu-tab-bar__item-text--selected':''}}" style="{{selectedIndex===index?textSelectedColor?'color:'+textSelectedColor:'':'color:'+textColor}}">
         {{item.text}}
       </view>
     </view>