[3.6] bpo-24813: IDLE: Add default title to help_about (GH-2366) (#2369)

Patch by Cheryl Sabella.
(cherry picked from commit 18ede06)
diff --git a/Lib/idlelib/editor.py b/Lib/idlelib/editor.py
index ab4f1a3..13b4a51 100644
--- a/Lib/idlelib/editor.py
+++ b/Lib/idlelib/editor.py
@@ -463,7 +463,7 @@
     def about_dialog(self, event=None):
         "Handle Help 'About IDLE' event."
         # Synchronize with macosx.overrideRootMenu.about_dialog.
-        help_about.AboutDialog(self.top,'About IDLE')
+        help_about.AboutDialog(self.top)
 
     def config_dialog(self, event=None):
         "Handle Options 'Configure IDLE' event."