feat(Dialog): add open、close event (#4633)

src/dialog/demo/index.vue

@@ -1,51 +1,21 @@
 <template>
   <demo-section>
     <demo-block :title="$t('alert1')">
-      <van-button
-        type="primary"
-        @click="onClickAlert"
-      >
-        {{ $t('alert1') }}
-      </van-button>
-      <van-button
-        type="primary"
-        @click="onClickAlert2"
-      >
-        {{ $t('alert2') }}
-      </van-button>
+      <van-button type="primary" @click="onClickAlert">{{ $t('alert1') }}</van-button>
+      <van-button type="primary" @click="onClickAlert2">{{ $t('alert2') }}</van-button>
     </demo-block>
 
     <demo-block :title="$t('confirm')">
-      <van-button
-        type="primary"
-        @click="onClickConfirm"
-      >
-        {{ $t('confirm') }}
-      </van-button>
+      <van-button type="primary" @click="onClickConfirm">{{ $t('confirm') }}</van-button>
     </demo-block>
 
     <demo-block :title="$t('asyncClose')">
-      <van-button
-        type="primary"
-        @click="onClickAsyncClose"
-      >
-        {{ $t('asyncClose') }}
-      </van-button>
+      <van-button type="primary" @click="onClickAsyncClose">{{ $t('asyncClose') }}</van-button>
     </demo-block>
 
     <demo-block :title="$t('componentCall')">
-      <van-button
-        type="primary"
-        @click="show = true"
-      >
-        {{ $t('componentCall') }}
-      </van-button>
-      <van-dialog
-        v-model="show"
-        :title="$t('title')"
-        show-cancel-button
-        :lazy-render="false"
-      >
+      <van-button type="primary" @click="show = true">{{ $t('componentCall') }}</van-button>
+      <van-dialog v-model="show" :title="$t('title')" show-cancel-button :lazy-render="false">
         <img :src="image">
       </van-dialog>
     </demo-block>
@@ -68,7 +38,7 @@ export default {
       alert2: 'Alert without title',
       confirm: 'Confirm dialog',
       asyncClose: 'Async Close',
-      componentCall: 'Component Call',
+      componentCall: 'Component Call'
     }
   },
 
@@ -121,7 +91,7 @@ export default {
 </script>
 
 <style lang="less">
-@import "../../style/var";
+@import '../../style/var';
 
 .demo-dialog {
   background-color: @white;