[bugfix] Popup: update overlay style & class (#349)

* fix: Tabbar icon line-height

* [new feature] progress add showPivot prop

* [new feature] TabItem support vue-router

* [new feature] update document header style

* [Doc] add toast english ducoment

* [bugfix] Search box-sizing wrong

* [Doc] update vant-demo respo

* [Doc] translate theme & demo pages

* [Doc] add Internationalization document

* [bugfix] remove unnecessary props

* [fix] optimize clickoutside

* [new feature] optimize find-parent

* [new feature]: change document title accordinng to language

* [new feature] Pagination code review

* [improvement] adjust icon-font unicode

* [improvement] Icon spinner color inherit

* [improvement] icon default width

* [bugfix] DateTimePicker validate date props

* [bugfix] Tab item text ellipsis

* [improvement] optimize single line ellipsis

* [Improvement] optimzie staticClass

* [Improvement] Button: use sfc instread of jsx

* [Improvement] update actionsheet close icon style

* fix: yarn.lock

* fix: icon test cases

* [bugfix] errors during ssr

* [Improvement] SubmitBar add left slot

* [new feature] ImagePreview support manually close

* fix: ImagePreview test case

* [Doc] add switch lang button in mobile

* [bugfix] Popup overlay style update

packages/mixins/popup/popup-context.js

@@ -2,14 +2,14 @@ const PopupContext = {
   idSeed: 1,
   zIndex: 2000,
   instances: {},
-  modalStack: [],
+  stack: [],
 
   plusKeyByOne(key) {
     return this[key]++;
   },
 
-  get topModal() {
-    return this.modalStack[this.modalStack.length - 1];
+  get top() {
+    return this.stack[this.stack.length - 1];
   }
 };