bpo-40275: Use new test.support helper submodules in tests (GH-21448)

diff --git a/Lib/test/test_webbrowser.py b/Lib/test/test_webbrowser.py
index 519a943..6ceb490 100644
--- a/Lib/test/test_webbrowser.py
+++ b/Lib/test/test_webbrowser.py
@@ -5,6 +5,7 @@
 import subprocess
 from unittest import mock
 from test import support
+from test.support import import_helper
 
 
 URL = 'http://www.example.com'
@@ -270,7 +271,7 @@
 
 class ImportTest(unittest.TestCase):
     def test_register(self):
-        webbrowser = support.import_fresh_module('webbrowser')
+        webbrowser = import_helper.import_fresh_module('webbrowser')
         self.assertIsNone(webbrowser._tryorder)
         self.assertFalse(webbrowser._browsers)
 
@@ -284,7 +285,7 @@
         self.assertEqual(webbrowser._browsers['example1'], [ExampleBrowser, None])
 
     def test_get(self):
-        webbrowser = support.import_fresh_module('webbrowser')
+        webbrowser = import_helper.import_fresh_module('webbrowser')
         self.assertIsNone(webbrowser._tryorder)
         self.assertFalse(webbrowser._browsers)
 
@@ -293,24 +294,24 @@
         self.assertIsNotNone(webbrowser._tryorder)
 
     def test_synthesize(self):
-        webbrowser = support.import_fresh_module('webbrowser')
+        webbrowser = import_helper.import_fresh_module('webbrowser')
         name = os.path.basename(sys.executable).lower()
         webbrowser.register(name, None, webbrowser.GenericBrowser(name))
         webbrowser.get(sys.executable)
 
     def test_environment(self):
-        webbrowser = support.import_fresh_module('webbrowser')
+        webbrowser = import_helper.import_fresh_module('webbrowser')
         try:
             browser = webbrowser.get().name
         except (webbrowser.Error, AttributeError) as err:
             self.skipTest(str(err))
         with support.EnvironmentVarGuard() as env:
             env["BROWSER"] = browser
-            webbrowser = support.import_fresh_module('webbrowser')
+            webbrowser = import_helper.import_fresh_module('webbrowser')
             webbrowser.get()
 
     def test_environment_preferred(self):
-        webbrowser = support.import_fresh_module('webbrowser')
+        webbrowser = import_helper.import_fresh_module('webbrowser')
         try:
             webbrowser.get()
             least_preferred_browser = webbrowser.get(webbrowser._tryorder[-1]).name
@@ -319,12 +320,12 @@
 
         with support.EnvironmentVarGuard() as env:
             env["BROWSER"] = least_preferred_browser
-            webbrowser = support.import_fresh_module('webbrowser')
+            webbrowser = import_helper.import_fresh_module('webbrowser')
             self.assertEqual(webbrowser.get().name, least_preferred_browser)
 
         with support.EnvironmentVarGuard() as env:
             env["BROWSER"] = sys.executable
-            webbrowser = support.import_fresh_module('webbrowser')
+            webbrowser = import_helper.import_fresh_module('webbrowser')
             self.assertEqual(webbrowser.get().name, sys.executable)