* Don't pass Blackdown to firefox-wrapper unless it is actually built.

svn path=/nixpkgs/branches/usability/; revision=4999

pkgs/development/compilers/blackdown/default.nix

@@ -6,4 +6,4 @@ if stdenv.system == "i686-linux"
       inherit stdenv fetchurl;
     }
   else
-    false
+    null

pkgs/top-level/all-packages.nix

@@ -1887,9 +1887,8 @@ rec {
     plugins = [
       MPlayerPlugin
       flashplayer
-      blackdown
 #      RealPlayer  # disabled by default for legal reasons
-    ];
+    ] ++ (if blackdown != null then [blackdown] else []);
   };
 
   firefoxWrapper = wrapFirefox firefox;