Is Firefox affected by "Meltdown"/"Spectre" (speculative execution security issues)

Firefox Development
#1

In the light of recent dark news (see CVE-2017-5753, CVE-2017-5715, and CVE-2017-5754): is Firefox affected directly by the mentioned “Meltdown”/“Spectre” CPU security issues?

#2

https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/

#3

Thanks!

I’ll follow the possible subsequent posts in that blog.