Fix select-to-speak options page.

Recent JS Modules migration caused <script> imported JS modules to fail.

AX-Relnotes: N/A

Bug: 1165431
Change-Id: I7ca66807f765daf83ba4105265d73b7d705f1535
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622754
Commit-Queue: Joel Riley <joelriley@google.com>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842739}

chrome/browser/resources/chromeos/accessibility/select_to_speak/options.html

@@ -108,7 +108,6 @@
       </div>
     </div>
 
-    <script src="prefs_manager.js"></script>
-    <script src="select_to_speak_options.js"></script>
+    <script type="module" src="select_to_speak_options.js"></script>
   </body>
 </html>