<select v-model="arr" v-bind:multiple="multiple">

### Vue.js version
2.1.10

### Reproduction Link
http://jsfiddle.net/myuvgsj8/

### What is actually happening?
Error:
VM281 vue.js:525 [Vue warn]: <select multiple v-model="arr"> expects an Array value for its binding, but got String 
(found in root instance)