It loads an empty editable web view with an edit toolbar. It makes easier to test the editor, editing commands and input methods.
Created attachment 254155 [details] Patch I made it a mode of MB instead of a new tool because that way we can share a lot of code, including the settings dialog and search bar. I've added an edit toolbar with some of the editing commands. For now, the buttons don't update their state according to the editor state, because we don't have API for that yet.
Committed r185312: <http://trac.webkit.org/changeset/185312>