firefox regressions

USN-3761-1 fixed vulnerabilities in Firefox. The update caused several
regressions affecting spellchecker dictionaries and search engines, which
were partially fixed by USN-3761-2. This update contains the remaining fix.

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, or execute
arbitrary code. (CVE-2018-12375, CVE-2018-12376, CVE-2018-12377,
CVE-2018-12378)

It was discovered that if a user saved passwords before Firefox 58 and
then later set a primary password, an unencrypted copy of these passwords
would still be accessible. A local user could exploit this to obtain
sensitive information. (CVE-2018-12383)