[orca] Fix traceback

[Joanmarie Diggs <joanied src gnome org>]

commit 6c29a0256143a0e2aed096f80abfdd4cdf90f929
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Mon Nov 16 23:34:18 2015 -0500

    Fix traceback

 src/orca/keybindings.py |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/src/orca/keybindings.py b/src/orca/keybindings.py
index 800ed60..cd88c24 100644
--- a/src/orca/keybindings.py
+++ b/src/orca/keybindings.py
@@ -294,9 +294,12 @@ class KeyBindings:
         """Removes the given KeyBinding instance from this set of keybindings.
         """
 
-        for i in range(0, len(self.keyBindings)):
-            if keyBinding == self.keyBindings[i]:
-                del self.keyBindings[i]
+        try:
+            i = self.keyBindings.index(keyBinding)
+        except:
+            pass
+        else:
+            del self.keyBindings[i]
 
     def removeByHandler(self, handler):
         """Removes the given KeyBinding instance from this set of keybindings.