[orca] Add sanity checks to thwart the impact of dead accessibles in WebKitGtk

[Joanmarie Diggs <joanied src gnome org>]

commit 259bc2c51f5cc9b17c7d9e9c02a12377a8e40718
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Wed Dec 14 12:43:14 2011 -0500

    Add sanity checks to thwart the impact of dead accessibles in WebKitGtk

 src/orca/script_utilities.py      |    6 +++++-
 src/orca/structural_navigation.py |    7 ++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)
---
diff --git a/src/orca/script_utilities.py b/src/orca/script_utilities.py
index 4cc2c7e..e141291 100644
--- a/src/orca/script_utilities.py
+++ b/src/orca/script_utilities.py
@@ -2824,7 +2824,11 @@ class Utilities:
         #
         # The keybindings in <full-path> should be separated by ":"
         #
-        bindingStrings = action.getKeyBinding(0).decode("UTF-8").split(';')
+        try:
+            bindingStrings = action.getKeyBinding(0).decode("UTF-8").split(';')
+        except AttributeError:
+            self._script.generatorCache[self.KEY_BINDING][obj] = ["", "", ""]
+            return self._script.generatorCache[self.KEY_BINDING][obj]
 
         if len(bindingStrings) == 3:
             mnemonic       = bindingStrings[0]
diff --git a/src/orca/structural_navigation.py b/src/orca/structural_navigation.py
index 15f2a85..f609873 100644
--- a/src/orca/structural_navigation.py
+++ b/src/orca/structural_navigation.py
@@ -1174,7 +1174,9 @@ class StructuralNavigation:
         index = obj.getIndexInParent() - 1
         if index >= 0:
             prevObj = obj.parent[index]
-            if prevObj.childCount:
+            if not prevObj:
+                debug.println(debug.LEVEL_FINE, 'Error: Dead Accessible')
+            elif prevObj.childCount:
                 prevObj = prevObj[prevObj.childCount - 1]
         elif not self._script.utilities.isSameObject(obj.parent, stopAncestor):
             prevObj = obj.parent
@@ -1205,6 +1207,9 @@ class StructuralNavigation:
             index = obj.getIndexInParent() + 1
             if 0 < index < obj.parent.childCount:
                 nextObj = obj.parent[index]
+                if not nextObj:
+                    debug.println(debug.LEVEL_FINE, 'Error: Dead Accessible')
+                    break
             elif not self._script.utilities.isSameObject(
                     obj.parent, stopAncestor):
                 obj = obj.parent