[orca] Handle another case of objects going away on us

[Joanmarie Diggs <joanied src gnome org>]

commit 5529865899a4c4bc435106f814442f9c920b6245
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Wed Jul 10 09:50:38 2019 -0400

    Handle another case of objects going away on us

 src/orca/scripts/web/script_utilities.py | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/orca/scripts/web/script_utilities.py b/src/orca/scripts/web/script_utilities.py
index a60c6d6ac..12fdd8ecb 100644
--- a/src/orca/scripts/web/script_utilities.py
+++ b/src/orca/scripts/web/script_utilities.py
@@ -239,6 +239,9 @@ class Utilities(script_utilities.Utilities):
         return pyatspi.findAncestor(obj, self.isDocument)
 
     def _getDocumentsEmbeddedBy(self, frame):
+        if not frame:
+            return []
+
         isEmbeds = lambda r: r.getRelationType() == pyatspi.RELATION_EMBEDS
         relations = list(filter(isEmbeds, frame.getRelationSet()))
         if not relations: