anchor.diff:        "--enable-system-hunspell"
         "--enable-system-pixman"
         "--enable-system-sqlite"
  +      "--enable-system-cairo"
         "--disable-crashreporter"
         "--disable-tests"
         "--disable-necko-wifi" # maybe we want to enable this at some point
         "--disable-installer"
         "--disable-updater"
         "--disable-gstreamer"
  -    ] ++ optional useSystemCairo "--enable-system-cairo";
  +    ];
   
   
     xulrunner = stdenv.mkDerivation rec {
  
positive.code: }:
  
  assert stdenv.gcc ? libc && stdenv.gcc.libc != null;
  assert useSystemCairo -> cairo != null;
  
  let optional = stdenv.lib.optional;
  in rec {
  
negative.code: , freetype, fontconfig, file, alsaLib, nspr, nss, libnotify
  , yasm, mesa, sqlite, unzip, makeWrapper, pysqlite
  , hunspell, libevent, libstartup_notification, libvpx
  , cairo
  , # If you want the resulting program to call itself "Firefox" instead
    # of "Shiretoko" or whatever, enable this option.  However, those
    # binaries may not be distributed without permission from the
  