component/headless-chromium: remove PATH and LD_LIBRARY_PATH from wrapper

component/headless-chromium/buildout.cfg

 [buildout]
 extends =
-# Build dependencies: note that bash, bzip2, getconf, grep, tar, and xz are already in /bin and /usr/bin
-# TODO: I think findutils is only here to expose xargs, which is already in /usr/bin, so see if we can get away with not requiring it
-# If the Python version doesn't default to 2, it might be necessary to include Python 2 as a component and then prepend it to the PATH or some similar trick.
+# Build dependencies:
   ../coreutils/buildout.cfg
   ../curl/buildout.cfg
   ../depot_tools/buildout.cfg
@@ -18,15 +16,6 @@ extends =
 parts =
   chromium-wrapper
 
-# Note that we'll need to proxy the websocket connection to the headless
-# Chromium shell, for several reasons. The web server that Chromium
-# spins up refuses HTTP requests unless the Host header is localhost or
-# an IP address [0], but we need SSL (i.e. wss://) because the frontend
-# page is loaded over HTTPS, and the mixed-content policy prevents us
-# from loading an ordinary ws:// connection.
-# [0] Security issue; see
-# https://bugs.chromium.org/p/chromium/issues/detail?id=813540
-
 # TODO: it may be more appropriate to manage our own copy of depot_tools, because I think some of the "gclient sync" commands may modify depot_tools, which could be problematic if other components or software releases depend on a shared copy, and at any rate it causes some build errors: when updating depot_tools, git complains because HEAD has been moved. Is there a way to guarantee a private copy? (This may be a moot point, since I don't think it's used by anything else, anyway, and trying again fixes the git issue.)
 
 # There's nothing special about version 91.0.4472.132. It just happened to be
@@ -83,9 +72,6 @@ configure-command =
 
 # You can run the headless Chromium shell using
 # ${:location}/headless-chromium --remote-debugging-port=1234
-# Note that your client browser must be Chromium-based, since Firefox
-# and Safari do not support constructible stylesheets yet (see e.g.
-# https://bugzilla.mozilla.org/show_bug.cgi?id=1520690).
 make-binary =
   autoninja -C ${:location} headless_shell
 environment =
@@ -98,11 +84,6 @@ runtime-libraries =
   ${nspr:location}/lib
   ${nss:location}/lib
 
-# Runtime path
-# TODO: see if this part is really necessary
-runtime-path =
-  ${fontconfig:location}/bin
-
 promises =
   ${:location}/headless_shell
 
@@ -136,14 +117,9 @@ install =
   part = self.buildout[os.path.basename(chromium)]
   with open(location, 'w') as f:
     f.write("""#!/bin/sh -e
-  cd {}
-  export LD_LIBRARY_PATH={}
-  export PATH={}:$PATH
   [ -z $FONTCONFIG_FILE ] && export FONTCONFIG_FILE=${default-font-config:rendered}
   exec ${chromium:path}/out/headless/headless_shell "$@"
   """.format(
     chromium,
-    ':'.join(part['runtime-libraries'].split()),
-    ':'.join(part['runtime-path'].split()),
   ))
     os.fchmod(f.fileno(), 0o755)