Upgrade to 1.0.27 breaks v-ref on a component with v-if

### Vue.js version

1.0.27
### Reproduction Link

https://jsfiddle.net/matfish2/7m1a799t/
### Steps to reproduce

a. Create a component
b. apply `v-ref` to it
c. apply `v-if` to it
### What is Expected?

`v-ref` should not break the code
### What is actually happening?

It throws an error:

`Uncaught TypeError: Cannot read property 'scope' of undefined`
