[HTTPSE 4.03 + FF 36.0.4] Losing the webpage address on rule toggle

This may reresult from the default FF's behaviour, inferior to other browsers in this respect.

1. Make an external programme open an address that has a HTTPSE rule assigned in FF in a new tab while the connection is down.
2. Toggle the rule.
3. Puff! The address is gone, nothing loads (or is unable to load), and the tab becomes an empty new tab.