Replace usage of six.moves.urllib with urllib

Also organize some of the imports. Now that Servo only uses Python 3,
this module is unnecessary. This is part of the gradual migration to
using only Python 3.

tests/jquery/run_jquery.py

@@ -14,7 +14,7 @@ import six.moves.BaseHTTPServer
 import six.moves.SimpleHTTPServer
 import six.moves.socketserver
 import threading
-import six.moves.urllib.parse
+import urllib
 import six
 
 # List of jQuery modules that will be tested.
@@ -149,13 +149,13 @@ def run_http_server():
             path = self.translate_path(self.path)
             f = None
             if os.path.isdir(path):
-                parts = six.moves.urllib.parse.urlsplit(self.path)
+                parts = urllib.parse.urlsplit(self.path)
                 if not parts.path.endswith('/'):
                     # redirect browser - doing basically what apache does
                     self.send_response(301)
                     new_parts = (parts[0], parts[1], parts[2] + '/',
                                  parts[3], parts[4])
-                    new_url = six.moves.urllib.parse.urlunsplit(new_parts)
+                    new_url = urllib.parse.urlunsplit(new_parts)
                     self.send_header("Location", new_url)
                     self.end_headers()
                     return None

tests/wpt/update/github.py

@@ -5,7 +5,8 @@
 from __future__ import print_function
 
 import json
-from six.moves.urllib.parse import urljoin
+import urllib
+
 requests = None
 
 class GitHubError(Exception):
@@ -36,7 +37,7 @@ class GitHub(object):
         return self._request("PUT", path, data=data)
 
     def _request(self, method, path, data=None):
-        url = urljoin(self.url_base, path)
+        url = urllib.parse.urljoin(self.url_base, path)
 
         kwargs = {"headers": self.headers,
                   "auth": self.auth}
@@ -96,7 +97,7 @@ class GitHubRepo(object):
         return PullRequest.from_number(self, number)
 
     def path(self, suffix):
-        return urljoin(self.url_base, suffix)
+        return urllib.parse.urljoin(self.url_base, suffix)
 
 
 class PullRequest(object):
@@ -126,7 +127,7 @@ class PullRequest(object):
         return cls(repo, data)
 
     def path(self, suffix):
-        return urljoin(self.repo.path("pulls/%i/" % self.number), suffix)
+        return urllib.parse.urljoin(self.repo.path("pulls/%i/" % self.number), suffix)
 
     @property
     def issue(self):
@@ -160,7 +161,7 @@ class Issue(object):
         return cls(repo, data)
 
     def path(self, suffix):
-        return urljoin(self.repo.path("issues/%i/" % self.number), suffix)
+        return urllib.parse.urljoin(self.repo.path("issues/%i/" % self.number), suffix)
 
     def add_label(self, label):
         """Add a label to the issue.

tests/wpt/update/upstream.py

@@ -4,7 +4,7 @@ import os
 import re
 import subprocess
 import sys
-import six.moves.urllib as urllib
+import urllib
 from six.moves import input
 from six import iteritems