image dragging in editor breaks image src in Firefox

[Vincent]

When you have a CKeditor in an HTML document with a <base href>, it breaks images when you drag an image in the editor.

I've set up a test case at ​http://ckeditor.02.swis.nl/js/ckeditor/_samples/replacebycode.html

This is a standard install. I've only changed replacebycode.html and inserted a <base href>.

Steps to see unwanted behaviour:

• Open the above URL in Firefox (3.6.3)
  
• Open the smiley dialog
  
• Click on a smiley to insert it in the editor
  
• Drag the smiley with the mouse to another location in the editor
  

=> Bug: image is broken in editor

This also happens with other images in the editor.

[Alfonso Martínez de Lizarrondo]

dup of #5218