Add initialization script for generic internal pages (#1099)

ext/bg/js/generic-page-main.js

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+(() => {
+    document.querySelector('#content-scroll-focus').focus();
+    document.documentElement.dataset.loaded = 'true';
+})();

ext/bg/legal.html

@@ -196,5 +196,8 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 </div>
 </div></div>
 
+<!-- Scripts -->
+<script src="/bg/js/generic-page-main.js"></script>
+
 </body>
 </html>