IE: The browser BACK button is not working properly

[Frederico Caldeira Knabben]

Regression. Confirmed with IE8:

1. Load any page, like ​http://www.google.com.
2. Load the replacebyclass sample in the same browser.
3. Click the browser BACK button. Note that the editor contents disappear.
4. Click the browser BACK button again. The previous page is loaded.

Expected results: the previous page should be loaded on step 3.

[Frederico Caldeira Knabben]

In fact, with the current trunk, an error is also thrown. Such error disappears after #5181.

[brooks]

I think this is caused by 'document.open()' in some iframes.

[Garry Yao]

Regression of [5395].

[Garry Yao]

IE mixes up history records of host page and the editing frame, Brooks contribute a secrete secondary param of document.open to help us flying under the radar, note that the patch also fixes a regression of [5450] where it's not able to load wysiwyg mode when switched from source.

[Frederico Caldeira Knabben]

I've committed this one with [5457] due to the severity and urgency of it.