Backport of Issue #14409 to 2.7

IDLE doesn't not execute commands from shell with default keybinding
for <Return>.
Patch by Roger Serwy.
diff --git a/Lib/idlelib/configHandler.py b/Lib/idlelib/configHandler.py
index 73487d5..dd13a0e 100644
--- a/Lib/idlelib/configHandler.py
+++ b/Lib/idlelib/configHandler.py
@@ -595,7 +595,7 @@
             '<<replace>>': ['<Control-h>'],
             '<<goto-line>>': ['<Alt-g>'],
             '<<smart-backspace>>': ['<Key-BackSpace>'],
-            '<<newline-and-indent>>': ['<Key-Return> <Key-KP_Enter>'],
+            '<<newline-and-indent>>': ['<Key-Return>', '<Key-KP_Enter>'],
             '<<smart-indent>>': ['<Key-Tab>'],
             '<<indent-region>>': ['<Control-Key-bracketright>'],
             '<<dedent-region>>': ['<Control-Key-bracketleft>'],