fixing a minor mem leak when disabling/uninstalling RR there were remaining window unload listeners that are now removed.
fixing a minor mem leak when disabling/uninstalling RR there were remaining window unload listeners that are now removed.

johancz/restartless-restart-ffext,johancz/restartless-restart-ffext,nsworld778/restartless-restart-ffext,oeekker/restartless-restart-ffext,mstange/restartless-restart-ffext,nsworld778/restartless-restart-ffext,jryans/restartless-restart-ffext,strel/restartless-restart-ffext,andreldm/restartless-restart-ffext,andreldm/restartless-restart-ffext,strel/restartless-restart-ffext,mstange/restartless-restart-ffext,mlissner/restartless-restart-ffext,jryans/restartless-restart-ffext,mlissner/restartless-restart-ffext,oeekker/restartless-restart-ffext