[orca] Don't attempt to find next/previous object of zombie

[Joanmarie Diggs <joanied src gnome org>]

commit d8e796677b993bb5290b4718643bed5bce3d6ff8
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Sat Apr 28 21:06:27 2018 -0400

    Don't attempt to find next/previous object of zombie

 src/orca/script_utilities.py |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/orca/script_utilities.py b/src/orca/script_utilities.py
index 12c124a..b3cf625 100644
--- a/src/orca/script_utilities.py
+++ b/src/orca/script_utilities.py
@@ -2366,7 +2366,7 @@ class Utilities:
     def findPreviousObject(self, obj):
         """Finds the object before this one."""
 
-        if not obj:
+        if not obj or self.isZombie(obj):
             return None
 
         for relation in obj.getRelationSet():
@@ -2391,7 +2391,7 @@ class Utilities:
     def findNextObject(self, obj):
         """Finds the object after this one."""
 
-        if not obj:
+        if not obj or self.isZombie(obj):
             return None
 
         for relation in obj.getRelationSet():