fix compatibility with 0.12

Author: yyx990803

src/mixin.js

@@ -1,14 +1,18 @@
 export default function (Vue) {
 
-  var _ = Vue.util
-
-  Vue.mixin({
+  const _ = Vue.util
+  const mixin = {
     created: function () {
       var route = this.$root.$route
       if (route) {
         route.router._children.push(this)
         if (!this.$route) {
-          _.defineReactive(this, '$route', route)
+          if (this._defineMeta) {
+            // 0.12 compat
+            this._defineMeta('$route', route)
+          } else {
+            _.defineReactive(this, '$route', route)
+          }
         }
       }
     },
@@ -18,5 +22,12 @@ export default function (Vue) {
         route.router._children.$remove(this)
       }
     }
-  })
+  }
+
+  if (Vue.mixin) {
+    Vue.mixin(mixin)
+  } else {
+    // 0.12 compat
+    Vue.options = _.mergeOptions(Vue.options, mixin)
+  }
 }

src/pipeline.js

@@ -128,7 +128,6 @@ export function activate (view, transition, depth, cb) {
   // itself as view.childView.
   let component = view.build({
     _meta: {
-      $route: view.vm.$route,
       $loadingRouteData: !!(dataHook && !waitForData)
     }
   })