[IE7-10] Magicline keyboard support for editor.enterMode BR

[Olek Nowodziński]

1. Visit ​http://ckeditor4.t/ckeditor/samples/plugins/enterkey/enterkey.html
2. Set enterMode to BR
3. Play with Ctrl+Alt+[ or ]
4. See Object doesn't support property or method 'setAttributes'

This is because the focus space is not an element anymore (BR mode), so it cannot have data-cke-magicline-hot attribute set.

Tested in IE9. Possibly also in other browsers.

[Olek Nowodziński]

The following Little Furry Monster should also be corrected :P

that.lastCmdDirection = element.getAttribute( 'data-cke-magicline-dir' ) === 'true' ? true : false

[Jakub Ś]

To reproduce:

1. Insert <div>Foo</div><div>Ba^r</div>
2. Press Ctrl+Alt+[ or Ctrl+Alt+]

I was able to reproduce this on latest master in IE7-10. All other browsers work well.

This is probably continuation for #9481