[orca] Fix c&p error in previous commit

[Joanmarie Diggs <joanied src gnome org>]

commit c4a489891cf280272845922d4590b5029797da24
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Sat Mar 11 10:09:24 2017 -0500

    Fix c&p error in previous commit

 src/orca/script_utilities.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/orca/script_utilities.py b/src/orca/script_utilities.py
index 874420f..1366beb 100644
--- a/src/orca/script_utilities.py
+++ b/src/orca/script_utilities.py
@@ -4233,7 +4233,7 @@ class Utilities:
         if not keyString in ["Up", "Down"]:
             return False
 
-        if self.isEditableDescendantOfComboBox(event.source):
+        if self.isEditableDescendantOfComboBox(orca_state.locusOfFocus):
             return False
 
         return not (mods & keybindings.CTRL_MODIFIER_MASK)