EDX436: fix bug that a toolbar editing discussion is incorrectly added in the courseware when user switches the page.
EDX436: fix bug that a toolbar editing discussion is incorrectly added in the courseware when user switches the page.

WatanabeYasumasa/edx-platform,yokose-ks/edx-platform,yokose-ks/edx-platform,yokose-ks/edx-platform,WatanabeYasumasa/edx-platform,yokose-ks/edx-platform,WatanabeYasumasa/edx-platform,WatanabeYasumasa/edx-platform,yokose-ks/edx-platform