[orca] Ignore bogus window:activate events from Gecko apps

[Joanmarie Diggs <joanied src gnome org>]

commit 84ba2b47d67442879913fbe9279ee5bbd1bd23d2
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Tue Feb 7 07:40:36 2017 -0500

    Ignore bogus window:activate events from Gecko apps

 src/orca/scripts/toolkits/Gecko/script.py |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/orca/scripts/toolkits/Gecko/script.py b/src/orca/scripts/toolkits/Gecko/script.py
index 1107b65..a1d25dd 100644
--- a/src/orca/scripts/toolkits/Gecko/script.py
+++ b/src/orca/scripts/toolkits/Gecko/script.py
@@ -318,6 +318,9 @@ class Script(web.Script):
     def onWindowActivated(self, event):
         """Callback for window:activate accessibility events."""
 
+        if not self.utilities.canBeActiveWindow(event.source):
+            return
+
         if super().onWindowActivated(event):
             return