The open-source developer also patched 28 security vulnerabilities, more than two-thirds of them marked "critical," Mozilla's highest threat rating, and revoked digital certificates that were initially thought to be in the hands of cyber criminals.
Other improvements in Firefox 18 included support for the high-resolution Retina screens used by Apple's MacBook Pro notebooks on OS X Lion and Mountain Lion, an option that lets users disable insecure content found on HTTPS-secured sites, and an opening round of support for WebRTC (for Web real-time communications), an in-development open-source API that adds browser-to-browser voice calls and video chat without requiring separate plug-ins.
Firefox 18 was missing one previously-promised addition, however: The integrated PDF viewer that was included in the browser's beta didn't make it into the final.
Mozilla also patched 28 vulnerabilities, 20 of them critical, with seven of the remaining labeled "high" and one pegged "moderate."
About a quarter of the bugs were reported by Abhishek Arya, who goes by the nickname "Inferno," of the Chrome security team, Mozilla said in an accompanying advisory. That makes two Firefox upgrades in a row where Arya has accounted for a significant chunk of the reported vulnerabilities Mozilla's patched.
Four of the eight flaws Arya reported to Mozilla were use-after-free vulnerabilities -- a type of memory management bug -- that Google's security engineers have become adept at finding in Chrome and other browsers.