anchor.diff:      ] ++ [
         "--enable-pie"
         "--with-pthreads"
  -    ] ++ optionals (nspr != null) [
         "--with-system-nspr"
         #"--enable-posix-nspr-emulation"
  -    ] ++ optionals (libevent != null) [
         "--with-system-libevent"
  -    ] ++ optionals (nss != null) [
         "--with-system-nss"
       ] ++ optionals (!isLinux && libjpeg != null) [
         # Enable libjpeg for platforms that don't support libjpeg-turbo
         "--with-system-jpeg"
  -    ] ++ optionals (zlib != null) [
  +    ] ++ [
         "--with-system-zlib"
  -    ] ++ optionals (bzip2 != null) [
         "--with-system-bz2"
  -    ] ++ optionals (libpng != null) [
         "--with-system-png"
  -    ] ++ optionals (hunspell != null) [
         "--enable-system-hunspell"
  -    ] ++ optionals (libffi != null) [
         "--enable-system-ffi"
  -    ] ++ [
         # Linking fails with shared js
         #"--enable-shared-js"
         #"--with-java-bin-path"
         "--enable-application=browser"
       ] ++ optionals enableOfficialBranding [
         "--enable-official-branding"
  -    ] ++ optionals (/*cairo != null &&*/ gtk3 != null) [
  +    ] ++ [
         "--enable-default-toolkit=cairo-gtk3"
         #"--without-x"
  -    ] ++ optionals (libstartup_notification != null) [
         "--enable-startup-notification"
  -    ] ++ [
         "--disable-gconf"
         #"--enable-libproxy"
         #"--enable-gnomeui" # ??? gnome2 ???
         "--enable-raw"
         #"--enable-eme"
  -    ] ++ optionals (libvpx != null) [
         "--with-system-libvpx"
  -    ] ++ optionals (alsaLib != null) [
         "--enable-alsa"
  -    ] ++ optionals (gstreamer != null && gst-plugins-base != null) [
         "--enable-gstreamer=1.0"
  -    ] ++ [
         "--disable-crashreporter"
       ] ++ optionals (isLinux && libjpeg != null)[
         "--enable-libjpeg-turbo"
  
positive.code:       # From firefox-40, using system cairo causes firefox to crash
        # frequently when it is doing background rendering in a tab.
        "--enable-system-cairo"
      ]*/ ++ optionals (pixman != null) [
        "--enable-system-pixman"
      ] ++ [
        #"--enable-necko-protocols={http,ftp,default,all,none}"
        "--disable-necko-wifi"
      ] ++ optionals (icu != null) [
        "--with-system-icu"
      ];
  
  
negative.code:       "--disable-updater"
        "--disable-tests"
        "--enable-content-sandbox"
        "--enable-system-sqlite"
        "--enable-safe-browsing"
        "--enable-url-classifier"
        "--enable-optimize"
        "--enable-approximate-location"
        "--enable-jemalloc"
        "--enable-strip"
        #"--enable-b2g-ril"
        #"--enable-b2g-bt"
  