Adding an Object of type LandingPage or of type DocumentationClass makes the title not editable with the In-place WYSIWYG Editor or the Inline Form Editor

To reproduce: 

1. Edit a page that has attached an object of type LandingPageClass or of type DocumentationClass using the In-place WYSIWYG Editor.
2. Try to edit the title field of the page.
3. Notice it's not possible to edit the field.

The same thing happens when trying to edit with the Inline Form Editor.

Example pages on xwiki.org where you can notice the issue:

• https://www.xwiki.org/xwiki/bin/edit/documentation/xs/user/base/page/view-page/WebHome (has object of type DocumentationClass attached)
• https://www.xwiki.org/xwiki/bin/edit/documentation/xs/user/base/page/WebHome (has object of type LandingPageClass attached)

See also the images below for examples.