message: refactor: speed up injection resolution
diff: @@ -41,14 +41,13 @@ export function resolveInject (inject: any, vm: Component): ?Object {
  // inject is :any because flow is not smart enough to figure out cached
  const result = Object.create(null)
  const keys = hasSymbol
  - ? Reflect.ownKeys(inject).filter(key => {
  - /* istanbul ignore next */
  - return Object.getOwnPropertyDescriptor(inject, key).enumerable
  - })
  + ? Reflect.ownKeys(inject)
  : Object.keys(inject)
  for (let i = 0; i < keys.length; i++) {
  const key = keys[i]
  + // #6574 in case the inject object is observed...
  + if (key === '__ob__') continue
  const provideKey = inject[key].from
  let source = vm
  while (source) {
  