[improvement] move overlay component (#2192)

packages/mixins/popup/Modal.vue

@@ -1,34 +0,0 @@
-<template>
-  <transition name="van-fade">
-    <div
-      v-show="visible"
-      class="van-modal"
-      :class="className"
-      :style="style"
-      @touchmove.prevent.stop
-      @click="$emit('click', $event)"
-    />
-  </transition>
-</template>
-
-<script>
-export default {
-  name: 'modal',
-
-  props: {
-    zIndex: Number,
-    visible: Boolean,
-    className: String,
-    customStyle: Object
-  },
-
-  computed: {
-    style() {
-      return {
-        zIndex: this.zIndex,
-        ...this.customStyle
-      };
-    }
-  }
-};
-</script>

packages/mixins/popup/manager.js

@@ -1,6 +1,6 @@
 import Vue from 'vue';
-import Modal from './Modal';
 import context from './context';
+import Overlay from '../../overlay';
 
 const defaultConfig = {
   className: '',
@@ -35,7 +35,7 @@ export default {
     let { modal } = context;
 
     if (!modal) {
-      modal = new (Vue.extend(Modal))({
+      modal = new (Vue.extend(Overlay))({
         el: document.createElement('div')
       });
       modal.$on('click', this.onClick);