swiftlatexpdftex.js and swiftlatexpdftex.wasm are builds of the SwiftLaTeX
pdfTeX engine. swiftlatexpdftex.js carries two local changes so the engine
works against a plain static file host:

  1. When a fetched TeX file has no `fileid` response header, the engine
     falls back to the requested file name.
  2. A 404 response is cached as a missing file (upstream only recognizes
     the 301 that its own package server returns), so absent packages are
     not re-requested on every compile.

  Source:  https://github.com/SwiftLaTeX/SwiftLaTeX
  Author:  Elliott Wen and contributors
  License: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0

They are bundled here so the PDF compiler runs entirely in the browser from
this origin. TeX packages are served from this site under /texlive/ and
cached by the worker; no third-party service is contacted at runtime.

The files under /texlive/ are a subset of TeX Live
(https://tug.org/texlive/), distributed under their respective licenses,
chiefly the LaTeX Project Public License and the Knuth License. They are
unmodified except for expl3.sty, a local stub documented in its header.