SiteLinksEditTool: Regenerating EditableValue prototype

(bug 50299) Regenerating the EditableValue prototype when entering a new value to reflect
the current set of site links covered by the SiteLinksEditToll instance.

Change-Id: I9fc651089306704dcc0dce15434470c6897d9c6c
Merge "SiteLinksEditTool: Regenerating EditableValue prototype"