Read selected state of a node by default

Bug: b/119523533
Test: steps described in the bug
Change-Id: I87d594d3655cd0de86a9a783eb9e5fc9ba2665c4
Reviewed-on: https://chromium-review.googlesource.com/c/1337221Reviewed-by: David Tseng <dtseng@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608471}

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

@@ -359,8 +359,8 @@ Output.PRESSED_STATE_MAP = {
 Output.RULES = {
   navigate: {
     'default': {
-      speak: `$name $node(activeDescendant) $value $state $restriction $role
-          $description`,
+      speak: `$name $node(activeDescendant) $value $state
+          $if($selected, @aria_selected_true) $restriction $role $description`,
       braille: ``
     },
     abstractContainer: {