nodejs: fix dev output

pkgs/development/web/nodejs/nodejs.nix

@@ -479,7 +479,7 @@ let
           ''}
 
           # install the missing headers for node-gyp
-          # TODO: add dev output and use propagatedBuildInputs instead of copying headers.
+          # TODO: use propagatedBuildInputs instead of copying headers.
           cp -r ${lib.concatStringsSep " " copyLibHeaders} $out/include/node
 
           # assemble a static v8 library and put it in the 'libv8' output
@@ -510,6 +510,9 @@ let
           Libs: -L$libv8/lib -lv8 -pthread -licui18n -licuuc
           Cflags: -I$libv8/include
           EOF
+        ''
+        + lib.optionalString (stdenv.hostPlatform == stdenv.buildPlatform) ''
+          cp -r $out/include $dev/include
         '';
 
       passthru.tests = {