watcher.run did not judge array

[gebilaoxiong]

Vue.js version

1.0.23

What is Expected?

hi

I remember the last time I mentioned the issuces, you also repaired.

I met this problem, and I found that code is reduction.

https://github.com/vuejs/vue/blob/dev/src/watcher.js#L253

I remember the last time with the array's judgment