[orca] Check for, and filter out, defunct objects when building elements list

[Joanmarie Diggs <joanied src gnome org>]

commit fbaf61a93993ff62f6277db9a2ad9946686c7893
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Fri Jan 20 08:39:47 2017 -0500

    Check for, and filter out, defunct objects when building elements list

 src/orca/structural_navigation.py |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/orca/structural_navigation.py b/src/orca/structural_navigation.py
index 3aae742..488f79f 100644
--- a/src/orca/structural_navigation.py
+++ b/src/orca/structural_navigation.py
@@ -364,6 +364,8 @@ class StructuralNavigationObject:
             return
 
         def _isValidMatch(x):
+            if script.utilities.isDead(x):
+                return False
             return not (script.utilities.isHidden(x) or script.utilities.isEmpty(x))
 
         objects = list(filter(_isValidMatch, objects))