fix: replace arrow functions for compatibility (#251)

Author: cccblade

lib/index.iife.js

@@ -19,7 +19,9 @@ var VueDemi = (function (VueDemi, Vue, VueCompositionAPI) {
     VueDemi.Vue2 = Vue
     VueDemi.version = Vue.version
     VueDemi.warn = Vue.util.warn
-    VueDemi.hasInjectionContext = () => !!VueDemi.getCurrentInstance()
+    VueDemi.hasInjectionContext = function() {
+      return !!VueDemi.getCurrentInstance()
+    }
     function createApp(rootComponent, rootProps) {
       var vm
       var provide = {}
@@ -72,7 +74,9 @@ var VueDemi = (function (VueDemi, Vue, VueCompositionAPI) {
       VueDemi.Vue = Vue
       VueDemi.Vue2 = Vue
       VueDemi.version = Vue.version
-      VueDemi.hasInjectionContext = () => !!VueDemi.getCurrentInstance()
+      VueDemi.hasInjectionContext = function() {
+        return !!VueDemi.getCurrentInstance()
+      }
     } else {
       console.error('[vue-demi] no VueCompositionAPI instance found, please be sure to import `@vue/composition-api` before `vue-demi`.')
     }

lib/v2.7/index.cjs

@@ -55,4 +55,6 @@ Object.keys(VueModule).forEach(function (key) {
 })
 
 // Not implemented https://github.com/vuejs/core/pull/8111, falls back to getCurrentInstance()
-exports.hasInjectionContext = () => !!VueModule.getCurrentInstance()
+exports.hasInjectionContext = function() {
+  return !!VueModule.getCurrentInstance()
+}

lib/v2/index.cjs

@@ -29,4 +29,6 @@ exports.install = install
 exports.version = Vue.version
 
 // Not implemented https://github.com/vuejs/core/pull/8111, falls back to getCurrentInstance()
-exports.hasInjectionContext = () => !!VueCompositionAPI.getCurrentInstance()
+exports.hasInjectionContext = function () {
+  return !!VueCompositionAPI.getCurrentInstance()
+}