use better context injection for 2.3

Author: yyx990803

lib/component-normalizer.js

@@ -39,7 +39,9 @@ module.exports = function normalizeComponent (
   var hook
   if (moduleIdentifier) { // server build
     hook = function (context) {
-      // context is injected if this is a cached call
+      // 2.3 injection
+      context = context || (this.$vnode && this.$vnode.ssrContext)
+      // 2.2 with runInNewContext: true
       if (!context && typeof __VUE_SSR_CONTEXT__ !== 'undefined') {
         context = __VUE_SSR_CONTEXT__
       }