fix: example navbar. close #160

Author: Tidyzq

Diff for: tools/demo/example/navbar/navbar.wxml

@@ -9,9 +9,9 @@
                 </block>
             </view>
             <view class="weui-tab__panel">
-                <view class="weui-tab__content" hidden="{{activeIndex != 0}}">选项一的内容</view>
-                <view class="weui-tab__content" hidden="{{activeIndex != 1}}">选项二的内容</view>
-                <view class="weui-tab__content" hidden="{{activeIndex != 2}}">选项三的内容</view>
+                <view class="weui-tab__content" style="display: {{activeIndex === 0 ? 'block' : 'none'}}">选项一的内容</view>
+                <view class="weui-tab__content" style="display: {{activeIndex === 1 ? 'block' : 'none'}}">选项二的内容</view>
+                <view class="weui-tab__content" style="display: {{activeIndex === 2 ? 'block' : 'none'}}">选项三的内容</view>
             </view>
         </view>
     </view>