support ES2015 Symbol in provide/inject

src/core/instance/inject.js

@@ -1,5 +1,9 @@
 /* @flow */
 
+import { isNative } from 'core/util/env'
+
+const hasReflect = typeof Reflect !== 'undefined' && isNative(Reflect.ownKeys)
+
 export function initInjections (vm: Component) {
   const provide = vm.$options.provide
   const inject: any = vm.$options.inject
@@ -12,7 +16,12 @@ export function initInjections (vm: Component) {
     // inject is :any because flow is not smart enough to figure out cached
     // isArray here
     const isArray = Array.isArray(inject)
-    const keys = isArray ? inject : Object.keys(inject)
+    const keys = isArray
+      ? inject
+      : hasReflect
+        ? Reflect.ownKeys(inject)
+        : Object.keys(inject)
+
     for (let i = 0; i < keys.length; i++) {
       const key = keys[i]
       const provideKey = isArray ? key : inject[key]

src/core/util/env.js

@@ -37,7 +37,7 @@ export const isServerRendering = () => {
 export const devtools = inBrowser && window.__VUE_DEVTOOLS_GLOBAL_HOOK__
 
 /* istanbul ignore next */
-function isNative (Ctor: Function): boolean {
+export function isNative (Ctor: Function): boolean {
   return /native code/.test(Ctor.toString())
 }
 

test/unit/features/options/inject.spec.js

@@ -1,4 +1,5 @@
 import Vue from 'vue'
+import { isNative } from 'core/util/env'
 
 describe('Options provide/inject', () => {
   let injected
@@ -124,4 +125,23 @@ describe('Options provide/inject', () => {
 
     expect(vm.foo).toBe(1)
   })
+
+  if (typeof Reflect !== 'undefined' && isNative(Reflect.ownKeys)) {
+    it('with Symbol keys', () => {
+      const s = Symbol()
+      const vm = new Vue({
+        template: `<child/>`,
+        provide: {
+          [s]: 123
+        },
+        components: {
+          child: {
+            inject: { s },
+            template: `<div>{{ s }}</div>`
+          }
+        }
+      }).$mount()
+      expect(vm.$el.textContent).toBe('123')
+    })
+  }
 })