Drop [IsIndex] IDL extended attribute from Speech types

LayoutTests/fast/speech/input-onspeechchange-event-expected.txt

Index: LayoutTests/fast/speech/input-onspeechchange-event-expected.txt
diff --git a/LayoutTests/fast/speech/input-onspeechchange-event-expected.txt b/LayoutTests/fast/speech/input-onspeechchange-event-expected.txt
index 3a28a36ed5650bfe3324306a83a094275707552a..4c3a7010688d526289e865c1bcecafbdd189469b 100644
--- a/LayoutTests/fast/speech/input-onspeechchange-event-expected.txt
+++ b/LayoutTests/fast/speech/input-onspeechchange-event-expected.txt
@@ -4,13 +4,14 @@ On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE
 
 
 PASS document.getElementById("speechInput").value is "Green eggs and ham"
-PASS window.event.results.length is 3
-PASS window.event.results[0].utterance is "Green eggs and ham"
-PASS window.event.results[0].confidence is 0.8
-PASS window.event.results[1].utterance is "Green x and ham"
-PASS window.event.results[1].confidence is 0.5
-PASS window.event.results[2].utterance is "3 x and am"
-PASS window.event.results[2].confidence is 0.2
+PASS results.length is 3
+PASS results[0].utterance is "Green eggs and ham"
+PASS results[0].confidence is 0.8
+PASS results[1].utterance is "Green x and ham"
+PASS results[1].confidence is 0.5
+PASS results[2].utterance is "3 x and am"
+PASS results[2].confidence is 0.2
+PASS results.item(-1) is null
 PASS successfullyParsed is true
 
 TEST COMPLETE