Did you install an additional certificate in your keychain perhaps? I don't see any Extended Validation fancy-pants business going on in my Chrome for https://www.eff.org/

If I recall correctly, Chrome and Safari use OS X's keychain system as its certificate store and Firefox does not. (Again, if I recall correctly, to manage certificates for Firefox, one must go to Preferences… > Advanced > Encryption.) I may be wrong. This is just off the top of my head. (Too preoccupied to verify.)