[improvement] declare functional sfc (#2695)

packages/cell-group/index.js

@@ -2,25 +2,21 @@ import { use } from '../utils';
 
 const [sfc, bem] = use('cell-group');
 
-export default sfc(
-  {
-    props: {
-      border: {
-        type: Boolean,
-        default: true
-      }
-    },
+export default sfc({
+  functional: true,
 
-    render(h, context) {
-      return (
-        <div
-          class={[bem(), { 'van-hairline--top-bottom': context.props.border }]}
-          {...context.data}
-        >
-          {context.children}
-        </div>
-      );
+  props: {
+    border: {
+      type: Boolean,
+      default: true
     }
   },
-  true
-);
+
+  render(h, context) {
+    return (
+      <div class={[bem(), { 'van-hairline--top-bottom': context.props.border }]} {...context.data}>
+        {context.children}
+      </div>
+    );
+  }
+});