Revert "Fix all Dart tests with JavaScript"

This reverts commit 7ef80d2b34dc21f662f7d74de59c7b330e55f339.

Going back to the pre-JS solution
Revert "First pass at attempting to support dart's newfound lack of key event data"

This reverts commit 945f18a4224892f91e25a8fca7b4bfc562029a3f.

Going back to the pre-JS solution
First pass at converting to KeyEvent
Switch to a single, KeyEvent shortcut stream

So that events are dispatched to the same stream on which all
listeners are listening.
Support a giant hack to store last keyCode

Until KeyEvent is fixed in Dart
Prep for Dart 1.0