link dialog breaks relative urls like href="foo"

[JasonWoof]

when you use the link dialog on a link like href="foo" then click OK (without changing anything) the link changes to: href="​http://foo"

This corrupts the page.

I solved this by changing the default protocol to "other". If you want to keep ​http:// as the default, you'll need to update the code that populates the link dialog, so if there's a href with a value, but no protocol, it sets the "protocol" dropdown to "other".

You can reproduce this bug by:

1) go to ​http://ckeditor.com/demo

2) select a word, click the link icon

3) set the protocol to "other" and the url to "foo"

4) click OK.

5) hit "source" and see that the href="foo"

6) click source again to go back to the normal view

7) click your link, and hit the "link" button again.

8) See that the "protocol" dropdown is now set to "​http://" (which is incorrect)

9) without changing anything, click "OK"

10) click the "source" button, and see that your link now has: href="​http://foo" (which is incorrect)

[Garry Yao]

Fixed with [4494].