[orca] Filter out document load events for images emitted by Gecko

[Joanmarie Diggs <joanied src gnome org>]

commit 1a608ddd10a9b606c5bd18b49ef24a5ead69e7fd
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Fri Sep 6 11:41:24 2019 +0200

    Filter out document load events for images emitted by Gecko

 src/orca/scripts/toolkits/Gecko/script.py           | 4 ++++
 src/orca/scripts/toolkits/Gecko/script_utilities.py | 3 +++
 2 files changed, 7 insertions(+)
---
diff --git a/src/orca/scripts/toolkits/Gecko/script.py b/src/orca/scripts/toolkits/Gecko/script.py
index 769ba86c5..38d1857af 100644
--- a/src/orca/scripts/toolkits/Gecko/script.py
+++ b/src/orca/scripts/toolkits/Gecko/script.py
@@ -100,6 +100,8 @@ class Script(web.Script):
         """Callback for object:state-changed:busy accessibility events."""
 
         if self.utilities.isNotRealDocument(event.source):
+            msg = "GECKO: Ignoring: Event source is not real document"
+            debug.println(debug.LEVEL_INFO, msg, True)
             return
 
         if super().onBusyChanged(event):
@@ -143,6 +145,8 @@ class Script(web.Script):
         """Callback for document:load-complete accessibility events."""
 
         if self.utilities.isNotRealDocument(event.source):
+            msg = "GECKO: Ignoring: Event source is not real document"
+            debug.println(debug.LEVEL_INFO, msg, True)
             return
 
         if super().onDocumentLoadComplete(event):
diff --git a/src/orca/scripts/toolkits/Gecko/script_utilities.py 
b/src/orca/scripts/toolkits/Gecko/script_utilities.py
index 683c62079..21406d919 100644
--- a/src/orca/scripts/toolkits/Gecko/script_utilities.py
+++ b/src/orca/scripts/toolkits/Gecko/script_utilities.py
@@ -175,6 +175,9 @@ class Utilities(web.Utilities):
         if uri.startswith("moz-extension"):
             return True
 
+        if not uri and "pixels" in name:
+            return True
+
         return False
 
     def canBeActiveWindow(self, window, clearCache=False):