[Firefox] Number of items in badge not updated when newtab url is about:blank

[hotdogman]

Steps to Reproduce

1. Open Firefox.
2. In about:config, set about.newtab.url to about:newtab, the default
3. Open a website where uBlock blocks something
4. Open a new tab

5. See that the number of blocked items in the badge has changed

6. Open Firefox.

7. In about:config, set about.newtab.url to about:blank
8. Open a website where uBlock blocks something
9. Open a new tab
10. See that the number of blocked items in the badge stays the same

Symptoms

Number of blocked items in badge does not change.

Preferences Different From Defaults

None. Tested with a clean firefox profile and a stock uBlock install.

Info

uBlock version:
    0.9.2.4-ab151/latest git master
Browser and version:
    Firefox 36.0.4
OS and version:
    Arch Linux x86_64

Other Extensions

• None.

And here's a quick 30 second video of the issue being reproduced.
http://a.pomf.se/rhemzm.webm

[gorhill]

@Deathamns, @AlexVallat

tabWatcher.onTabSelect skips vAPI.tabs.onNavigation at line 345 because busyFlags is 3 instead of the expected 0.

[Deathamns]

50804eb.

[AlexVallat]

So I guess what's happening is that although the tab is still loading when it's switched to, it never fires updates the badge when it finishes loading? When I try it (on Nightly) it doesn't update the badge immediately on switch, but then updates it about half a second later.

Edit: adding some tracing and trying some more, I have found that it can get into a state where browser.webNavigation.busyFlags is undefined which is not helpful. Could just assume that if it's undefined it counts as not busy, I suppose...