dillon1000/react

Improve Browser Support for `wheel` Event

This improved browser support for the `wheel` event.

 - Try to use `wheel` event (DOM Level 3 Specification).
 - Fallback to `mousewheel` event.
 - Fallback to `DOMMouseWheel` (older Firefox).

Also, since `wheel` is the standard event name, let's use that in React.

NOTE: The tricky part was detecting if `wheel` is supported for IE9+ because `onwheel` does not exist.

Test Plan:
Execute the following in the console on a page with React:

  var React = require('React');
  React.renderComponent(React.DOM.div({
    style: {
      width: 10000,
      height: 10000
    },
    onWheel: function() {
      console.log('wheel');
    }
  }, null), document.body);

Verified that mousewheel events are logged to the console.
Verified in IE8-10, Firefox, Chrome, and Safari.