减少不必要的代码

Former-commit-id: 8c704c1c9e29c1f8887eb3b899977b35b8a5e4bd

src/plugin/open/index.js

@@ -0,0 +1,8 @@
+export default {
+  install (Vue, options) {
+    // 打开一个url
+    Vue.prototype.$open = (url = 'https://github.com/d2-projects') => {
+      window.open(url)
+    }
+  }
+}