Be more nodejs friendly, tweak some lines

src/core/index.js

@@ -3,11 +3,12 @@ import deepExtend from "deep-extend"
 import System from "core/system"
 import win from "core/window"
 import ApisPreset from "core/presets/apis"
+
 import * as AllPlugins from "core/plugins/all"
 import { parseSearch } from "core/utils"
 
-if (process.env.NODE_ENV !== "production") {
-  window.Perf = require("react-addons-perf")
+if (process.env.NODE_ENV !== "production" && typeof window !== "undefined") {
+  win.Perf = require("react-addons-perf")
 }
 
 // eslint-disable-next-line no-undef