[bugfix] Popup modal display error

packages/mixins/popup/popup-context.js

@@ -1,35 +1,15 @@
-import Vue from 'vue';
-
-const _global = Vue.prototype.$isServer ? global : window;
-
-const DEFAULT_CONTEXT = {
+const PopupContext = {
   idSeed: 1,
   zIndex: 2000,
-  hasModal: false,
   instances: {},
-  modalStack: []
-};
-
-if (!_global.popupContext) {
-  _global.popupContext = {
-    ...DEFAULT_CONTEXT
-  };
-}
-
-const PopupContext = {
-  getContext(key) {
-    return _global.popupContext[key];
-  },
-
-  setContext(key, value) {
-    _global.popupContext[key] = value;
-  },
+  modalStack: [],
 
   plusKeyByOne(key) {
-    const oldVal = +_global.popupContext[key];
-    _global.popupContext[key] = oldVal + 1;
+    return this[key]++;
+  },
 
-    return oldVal;
+  get topModal() {
+    return this.modalStack[this.modalStack.length - 1];
   }
 };