restrict to current window's tabs; fix a problem with last-pinned-tab's index
restrict to current window's tabs; fix a problem with last-pinned-tab's index

evolighting/webextensions-examples,evolighting/webextensions-examples,matthewjwein/webextensions-examples,mdn/webextensions-examples,andymckay/webextensions-examples,matthewjwein/webextensions-examples,mdn/webextensions-examples,mdn/webextensions-examples,andymckay/webextensions-examples,anaran/webextensions-examples,anaran/webextensions-examples,evolighting/webextensions-examples,matthewjwein/webextensions-examples