Motivation for this change

So I can build https://github.com/joeferner/node-java in my project. node-gyp et al are included in the node 6 and node 8 node-packages.

Changed pkgs/development/node-packages/node-packages-v10.json and ran pkgs/development/node-packages/generate.sh as per instructions, then reverted the changes to node 6 and node 8 as I don't want to change anything there.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Fits CONTRIBUTING.md.