I think you want to remove this because it messes up `pushState`(?), but I don't think it's quite so simple. In Chrome, the page action icon automatically gets cleared when the page changes. In Safari, this isn't the case. Instead, `validate` gets called sometime around the page change to tell us to change the icon. While we clear the translators in `onPageLoad` above, Safari doesn't inject anything on non-HTML (i.e. PDF) page loads, so `onPageLoad` never gets triggered, the translators never get cleared, and we end up showing the translate icon on the PDF even though the button can't do anything. I'll have to think more about how to handle this appropriately.