[orca/gnome-3-16] Initialize and reset Gecko's line contents cache to an empty list

[Joanmarie Diggs <joanied src gnome org>]

commit d42531ffeca0f18720d6976e27f3f9d31f9346e2
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Fri May 15 16:06:09 2015 -0400

    Initialize and reset Gecko's line contents cache to an empty list
    
    Fixes a traceback that causes Orca to go silent after Gecko kills
    an accessible in the current page.

 src/orca/scripts/toolkits/Gecko/script.py |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/orca/scripts/toolkits/Gecko/script.py b/src/orca/scripts/toolkits/Gecko/script.py
index dce94c9..a88dc66 100644
--- a/src/orca/scripts/toolkits/Gecko/script.py
+++ b/src/orca/scripts/toolkits/Gecko/script.py
@@ -174,7 +174,7 @@ class Script(default.Script):
         # we can speak and braille this information without having to call
         # getLineContentsAtOffset() twice.
         #
-        self.currentLineContents = None
+        self.currentLineContents = []
 
         # For really large objects, a call to getAttributes can take up to
         # two seconds! This is a Firefox bug. We'll try to improve things
@@ -1452,7 +1452,7 @@ class Script(default.Script):
     def _destroyLineCache(self):
         """Removes all of the stored lines."""
 
-        self.currentLineContents = None
+        self.currentLineContents = []
         self.currentAttrs = {}
 
     def presentLine(self, obj, offset):