Replace result incorrect

[Garry Yao]

Reproducing Procedures

1. Open the replace by class example page in FF;
2. Load the content with the following:

   <p>
   	You're testing <span>ckeditor</span> undo system.</p>
   

3. Open find/replace dialog and enter 'ckeditor' into 'Find What', click Replace buttton;
4. Fill in 'v3' into 'Relace With' and click Replace button again.
   • Actual Result:

     <p>
     	You're testing v3</p>