[orca] Web: Only generate ancestors for the first item on a new line

[Joanmarie Diggs <joanied src gnome org>]

commit 9c3001d39eb1a8c7dc56e95ef04d569396f075a4
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Mon Feb 3 15:57:02 2020 -0500

    Web: Only generate ancestors for the first item on a new line
    
    Usually the ancestors for subsequent objects on the line have not
    changed, but the work of determining that can hurt performance.

 src/orca/scripts/web/speech_generator.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/src/orca/scripts/web/speech_generator.py b/src/orca/scripts/web/speech_generator.py
index d8501568e..bf4369f90 100644
--- a/src/orca/scripts/web/speech_generator.py
+++ b/src/orca/scripts/web/speech_generator.py
@@ -45,6 +45,18 @@ class SpeechGenerator(speech_generator.SpeechGenerator):
     def __init__(self, script):
         super().__init__(script)
 
+    def _generateOldAncestors(self, obj, **args):
+        if args.get('index', 0) > 0:
+            return []
+
+        return super()._generateOldAncestors(obj, **args)
+
+    def _generateNewAncestors(self, obj, **args):
+        if args.get('index', 0) > 0:
+            return []
+
+        return super()._generateNewAncestors(obj, **args)
+
     def _generateAncestors(self, obj, **args):
         if not self._script.utilities.inDocumentContent(obj):
             return super()._generateAncestors(obj, **args)