Switched to DOM_VK variables instead of numbers for event codes
Removed webkit specific 'prevent default' code, tinymce.ui.KeyboardNavigation cancels all events by default as of commit b52bb0784c702504e9d1090e311e8bd684e9ab59
Turn off keyboard handling of up and down in native list boxes so the event falls through to the native implementation
move variables to top of function
changelog for Fixed edgecase on up/down arrow keys scrolling with native lists.