[2.0] Internet Explorer select elements display first option by default

[fergaldoyle]

Similar to issue #2983 which was logged for 1.x

Vue.js version

2.0 rc

Reproduction Link

http://codepen.io/anon/pen/GjqwaA?editors=1010#0

Steps to reproduce

Open the above codepen in IE

What is Expected?

The visible select elements should be empty / have no option selected

What is actually happening?

The visible select elements all have "AAA" selected. The underlying model is not in sync. Interestingly when you click the "show" button, the select elements display as expected.