Reload Discarded Tabs per Irv66

If you use a session manager for Firefox like "Tab Session Manager", you can save and restore your tab sessions without history.

However, there is currently a limitation when trying to restore a session when using the tabs.create() function with the "discarded" property. (See https://bugzilla.mozilla.org/show_bug.cgi?id=1475240 - Allow setting favicon when creating discarded tabs) In this case, all of your tabs can be created quickly and in the discarded state but the favicon is simply set to the default globe and doesn't get updated until the tab is loaded. Therefore, your restored tab session will simply look like a collection of default globe tabs until each tab is loaded for the first time.

This addon can be used right after restoring your session (by clicking on the addon icon) and it simply traverses all of your discarded tabs one by one to load the favicon then simply discards them again so you can more easily visually identify your tabs.