firefox regressions

USN-4278-1 fixed vulnerabilities in Firefox. The update introduced various
minor regressions. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

Multiple security issues were discovered in Firefox. If a user were tricked
in to opening a specially crafted website, an attacker could potentially
exploit these to cause a denial of service, conduct cross-site scripting
(XSS) attacks, or execute arbitrary code.