Vue.js version

2.0.5

Reproduction Link

https://jsfiddle.net/crjL62kL/4/

Steps to reproduce

1 Create an array
2 Add something to Array.prototype or add some property to the array obj
3 use this array as data and trigger mergeData

What is Expected?

the array is merged withou error and without key-values in prototype

What is actually happening?

TypeError or key-values in prototype is copy to the array