Use rustdoc --document-private-item instead of deprecated flags

… and use $RUSTDOCFLAGS instead of $RUSTDOC with a wrapper script

etc/rustdoc-with-private

@@ -1,4 +0,0 @@
-#!/bin/sh
-# Skip the strip-private and strip-hidden rustdoc passes
-# https://github.com/rust-lang/rust/issues/15347
-rustdoc --no-defaults --passes collapse-docs --passes unindent-comments --passes strip-priv-imports "$@"

python/servo/command_base.py

@@ -486,7 +486,7 @@ class CommandBase(object):
         if hosts_file_path:
             env['HOST_FILE'] = hosts_file_path
 
-        env['RUSTDOC'] = path.join(self.context.topdir, 'etc', 'rustdoc-with-private')
+        env['RUSTDOCFLAGS'] = "--document-private-items"
 
         if self.config["build"]["rustflags"]:
             env['RUSTFLAGS'] = env.get('RUSTFLAGS', "") + " " + self.config["build"]["rustflags"]