Make controlled components and bubbling work in IE

Fixes #708.

Test Plan:
In IE9, tested a controlled text input with the event handler on a containing element, as in the fiddle linked in the original issue. Also tested a controlled radio button as the logic there differs within ReactDOMInput. In both cases, I was able to interact with the controls.
Merge pull request #721 from spicyj/change-bubble-ie

Make controlled components and bubbling work in IE