Load the proper editor when the user goes to the Edit Post screen with Go Back or Go Forward

[azaozz]

When the browser's Go Back or Go Forward buttons are used the browser usually loads the page from memory cache. If the loaded page has an editor that was switched (Visual to Text or Text to Visual), getUserSetting('editor') would return the new value, but the page's HTML will be set for the previous value.

This could result in either showing the Quicktags toolbar above the TinyMCE toolbar or in loading the content without <p> tags in TinyMCE.

[azaozz]

In 27364:

Editor: look at the class of the wrapper element instead of getUserSetting('editor') to determine the default editor, fixes #27257