Include posInSet and setSize in tab output rule

chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js

Index: chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js
diff --git a/chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js b/chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js
index 1a5df37c83dac354dfcecbf69f4239edde35c6c0..84e99215d7150a3dc046190cebad4af40f8d3f1d 100644
--- a/chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js
+++ b/chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js
@@ -540,7 +540,8 @@ Output.RULES = {
           '@describe_switch_off($name)) $description $state'
     },
     tab: {
-      speak: '@describe_tab($name) $state $description'
+      speak: '@describe_tab($name) $state $description ' +
+          '$if($setSize, @describe_index($posInSet, $setSize))',
     },
     table: {
       enter: '@table_summary($name, $tableRowCount, $tableColumnCount) ' +