[orca] Be sure we have contents to display before attempting to display them

[Joanmarie Diggs <joanied src gnome org>]

commit 27dbefbe7cd435de543d24dbfdf16308c897e628
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Sat Mar 11 10:40:05 2017 -0500

    Be sure we have contents to display before attempting to display them

 src/orca/scripts/web/script.py |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/orca/scripts/web/script.py b/src/orca/scripts/web/script.py
index 52f40c5..df337c6 100644
--- a/src/orca/scripts/web/script.py
+++ b/src/orca/scripts/web/script.py
@@ -869,7 +869,11 @@ class Script(default.Script):
             return
 
         line = self.getNewBrailleLine(clearBraille=True, addLine=True)
-        regions, focusedRegion = self.brailleGenerator.generateContents(contents)
+        contents = self.brailleGenerator.generateContents(contents)
+        if not contents:
+            return
+
+        regions, focusedRegion = contents
         for region in regions:
             self.addBrailleRegionsToLine(region, line)