Do not update toolbar button state inside tab 'activated' event handler
Do not update toolbar button state inside tab 'activated' event handler

According to kmag, webextension buttons have per-tab state, so setting
the button enabled or disabled on update should be enough. Updating the
icon on tab activated may be causing performance issues.

See https://bugzilla.mozilla.org/show_bug.cgi?id=1361792 for details.

Also remove tab.active check, so that non-active tabs can catch button
updates (https://bugzilla.mozilla.org/show_bug.cgi?id=1362234#c2)

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