Can not modify target window properties of a link

[damo]

When the target option of a link is Popup Window, the values for the Popup Window Features and sizes can not be modified after the first edit of the properties.

To reproduce:
1. Create a new link
2. Edit the target as Popup Window
3. Select some Popup Window Features
4. Set a width and height
5. Click OK
6. Remove editor & create editor
7. Edit the link
8. Modify the original edits to target, including width and height
9. Click OK
10. Edit the link again to confirm options at step 8. are kept.

Result: The options are not modified in step 8. but remain as set in steps 3 & 4

[damo]

In FF, Popup Window Features, width, height, left position, right position and Popup Window Name do not get updated.

In IE, only Popup Window Name does not get updated.

[garry.yao]

Ticket Test added at :
 http://ckeditor.t/tt/4901/1.html.

[garry.yao]

Fixed with [4821].