[Read Aloud] Scroll the current highlight into view when we go backward

Fixed: 350816316
Change-Id: If4b4bfd0e82c71e9cffa072b5466efc135415b00
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5677327
Commit-Queue: Lauren Winston <lwinston@google.com>
Reviewed-by: Lauren Winston <lwinston@google.com>
Commit-Queue: Kristi Saney <kristislee@google.com>
Auto-Submit: Kristi Saney <kristislee@google.com>
Cr-Commit-Position: refs/heads/main@{#1323051}