fix JS events being rebound during back/next cycles. MB-4458
fix JS events being rebound during back/next cycles. MB-4458

Change-Id: I930344d98dd846460210991dc497fd647afd4435
Reviewed-on: http://review.couchbase.org/11054
Tested-by: Volker Mische <fb414f8ac0dbbf87663550ae4ef5fc95b1041941@gmail.com>
Reviewed-by: Volker Mische <fb414f8ac0dbbf87663550ae4ef5fc95b1041941@gmail.com>

membase/ns_server,membase/ns_server,vzasade/ns_server,vzasade/ns_server,t3rm1n4l/ns_server,pavel-blagodov/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,nimishzynga/ns_server,mschoch/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,vzasade/ns_server,ceejatec/ns_server,vzasade/ns_server,daverigby/ns_server,ceejatec/ns_server,pavel-blagodov/ns_server,pavel-blagodov/ns_server,nimishzynga/ns_server,daverigby/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,mschoch/ns_server,daverigby/ns_server,ceejatec/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,mschoch/ns_server,daverigby/ns_server,membase/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server