Prior to this commit, the script codegen makefile relied on an intermediary pythonpath.py file that handled python dependencies and incorporated a couple hacks to get the codegen building working. This commit removes that intermediary file and attempts to make the script codegen build process cleaner. Source-Repo: https://github.com/servo/servo Source-Revision: 493da96cae7cc0e3b533fc1f01cc0c5e38a27e02