Undoing replaced text restores fake selection HTML

[martinkou]

This bug was discovered while working on #2150. It will be fixed with the patch of #2150 since the find/replace logic of the dialog is being rewritten right now.

To reproduce:

1. Open sample01.html.
2. Open the Replace dialog.
3. Look for "some" and fill in "same" for the replacement text.
4. Press "Replace" twice so that the "some" in the document is replaced.
5. Close the dialog.
6. Press undo once.
7. The "some" in the editing document is highlighted... but it's a fake highlight done by CSS effects and it shouldn't be saved by the undo system at all.

[martinkou]

Fixed along the ticket #2150.