anchor.diff:        "--disable-updater"
         "--enable-jemalloc"
         "--disable-gconf"
  +      "--enable-default-toolkit=cairo-gtk2"
       ]
       ++ lib.optional enableGTK3 "--enable-default-toolkit=cairo-gtk3"
       ++ (if debugBuild then [ "--enable-debug" "--enable-profiling" ]
  
positive.code: 
    firefox-unwrapped = common {
      pname = "firefox";
      version = "45.0.2";
      sha512 = "8c0b7afb41a1a405fe499299d1a8b1138dac52b9ad67bfc8761b70a26f330581c2aa1d76d67075896ec3a0c3f5367b8b58365ebc8b3a01f801fa37071b3de526";
    };
  
    firefox-esr-unwrapped = common {
  
negative.code:       "--with-system-nspr"
        "--with-system-nss"
        "--with-system-libevent"
        #"--with-system-libvpx" # needs 1.5.0
        "--with-system-png" # needs APNG support
        "--with-system-icu"
        "--enable-system-ffi"
  