修复使用全局变量，导致部分cell边框不出现的问题 (#237)

example/pages/cell/index.js

@@ -2,7 +2,8 @@ var Zan = require('../../dist/index');
 
 Page(Object.assign({}, Zan.Switch, {
   data: {
-    checked: false
+    checked: false,
+    show: true
   },
 
   onLoad() {

example/pages/cell/index.wxml

@@ -31,10 +31,12 @@
       <zan-cell title="只显示箭头" is-link></zan-cell>
       <zan-cell title="跳转到首页" is-link url="/pages/dashboard/index"></zan-cell>
       <zan-cell title="只有 footer 点击有效" is-link url="/pages/dashboard/index" only-tap-footer></zan-cell>
+      <block wx:if="{{ show }}">
         <zan-cell title="单行列表" label="附加描述" value="详细信息"></zan-cell>
         <zan-cell title="表单">
           <input slot="footer" type="digit" placeholder="带小数点的数字键盘"/>
         </zan-cell>
+      </block>
       <zan-cell title="开关">
         <switch slot="footer" checked/>
       </zan-cell>

packages/cell-group/index.js

@@ -1,5 +1,3 @@
-let cellUpdateTimeout = 0;
-
 Component({
   relations: {
     '../cell/index': {
@@ -16,15 +14,19 @@ Component({
     }
   },
 
+  data: {
+    cellUpdateTimeout: 0
+  },
+
   methods: {
     _updateIsLastCell() {
       // 用 setTimeout 减少计算次数
-      if (cellUpdateTimeout > 0) {
+      if (this.data.cellUpdateTimeout > 0) {
         return;
       }
 
-      cellUpdateTimeout = setTimeout(() => {
-        cellUpdateTimeout = 0;
+      const cellUpdateTimeout = setTimeout(() => {
+        this.setData({ cellUpdateTimeout: 0 });
         let cells = this.getRelationNodes('../cell/index');
 
         if (cells.length > 0) {
@@ -35,6 +37,8 @@ Component({
           });
         }
       });
+
+      this.setData({ cellUpdateTimeout });
     }
   }
 });