[orca] Be sure we have sayAll contents before attempting fast forward or rewind

[Joanmarie Diggs <joanied src gnome org>]

commit 66f1be38765a4d02f5e8df2c35fa88c637bdf171
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Thu Feb 23 04:03:16 2017 -0500

    Be sure we have sayAll contents before attempting fast forward or rewind

 src/orca/scripts/web/script.py |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/src/orca/scripts/web/script.py b/src/orca/scripts/web/script.py
index da240ad..074575a 100644
--- a/src/orca/scripts/web/script.py
+++ b/src/orca/scripts/web/script.py
@@ -656,7 +656,11 @@ class Script(default.Script):
         if not _settingsManager.getSetting('rewindAndFastForwardInSayAll'):
             return False
 
-        obj, start, end, string = self._sayAllContents[0]
+        try:
+            obj, start, end, string = self._sayAllContents[0]
+        except IndexError:
+            return False
+
         orca.setLocusOfFocus(None, obj, notifyScript=False)
         self.utilities.setCaretContext(obj, start)
 
@@ -671,7 +675,11 @@ class Script(default.Script):
         if not _settingsManager.getSetting('rewindAndFastForwardInSayAll'):
             return False
 
-        obj, start, end, string = self._sayAllContents[-1]
+        try:
+            obj, start, end, string = self._sayAllContents[-1]
+        except IndexError:
+            return False
+
         orca.setLocusOfFocus(None, obj, notifyScript=False)
         self.utilities.setCaretContext(obj, end)