fix(feed): 修正轮播动画方向（从底部进入、从顶部退出）

cfc-frontend/components/FamilyFeed.vue

@@ -129,9 +129,12 @@ export default {
       return 'feed-item-entering'
     },
     itemInlineStyle: function() {
-      var style = {}
-      if (this.state === 'entering') { style.transition = 'none' }
-      return style
+      // leaving 时保持 transition:none，防止从顶部跳到下一条时产生反向动画
+      // entering 时也保持 none，让下一帧再恢复 transition 做入场动画
+      if (this.state === 'entering' || this.state === 'leaving') {
+        return { transition: 'none' }
+      }
+      return {}
     },
     detailMeta: function() {
       var type = (this.detail && this.detail.type) || ''