diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/widgets/class-wp-widget-pages.php
--- a/wp/wp-includes/widgets/class-wp-widget-pages.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-includes/widgets/class-wp-widget-pages.php	Tue Dec 15 13:49:49 2020 +0100
@@ -40,7 +40,8 @@
 	 * @param array $instance Settings for the current Pages widget instance.
 	 */
 	public function widget( $args, $instance ) {
-		$title = ! empty( $instance['title'] ) ? $instance['title'] : __( 'Pages' );
+		$default_title = __( 'Pages' );
+		$title         = ! empty( $instance['title'] ) ? $instance['title'] : $default_title;
 
 		/**
 		 * Filters the widget title.
@@ -56,22 +57,22 @@
 		$sortby  = empty( $instance['sortby'] ) ? 'menu_order' : $instance['sortby'];
 		$exclude = empty( $instance['exclude'] ) ? '' : $instance['exclude'];
 
-		if ( $sortby == 'menu_order' ) {
+		if ( 'menu_order' === $sortby ) {
 			$sortby = 'menu_order, post_title';
 		}
 
-		/**
-		 * Filters the arguments for the Pages widget.
-		 *
-		 * @since 2.8.0
-		 * @since 4.9.0 Added the `$instance` parameter.
-		 *
-		 * @see wp_list_pages()
-		 *
-		 * @param array $args     An array of arguments to retrieve the pages list.
-		 * @param array $instance Array of settings for the current widget.
-		 */
 		$out = wp_list_pages(
+			/**
+			 * Filters the arguments for the Pages widget.
+			 *
+			 * @since 2.8.0
+			 * @since 4.9.0 Added the `$instance` parameter.
+			 *
+			 * @see wp_list_pages()
+			 *
+			 * @param array $args     An array of arguments to retrieve the pages list.
+			 * @param array $instance Array of settings for the current widget.
+			 */
 			apply_filters(
 				'widget_pages_args',
 				array(
@@ -89,11 +90,29 @@
 			if ( $title ) {
 				echo $args['before_title'] . $title . $args['after_title'];
 			}
+
+			$format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';
+
+			/** This filter is documented in wp-includes/widgets/class-wp-nav-menu-widget.php */
+			$format = apply_filters( 'navigation_widgets_format', $format );
+
+			if ( 'html5' === $format ) {
+				// The title may be filtered: Strip out HTML and make sure the aria-label is never empty.
+				$title      = trim( strip_tags( $title ) );
+				$aria_label = $title ? $title : $default_title;
+				echo '<nav role="navigation" aria-label="' . esc_attr( $aria_label ) . '">';
+			}
 			?>
-		<ul>
-			<?php echo $out; ?>
-		</ul>
+
+			<ul>
+				<?php echo $out; ?>
+			</ul>
+
 			<?php
+			if ( 'html5' === $format ) {
+				echo '</nav>';
+			}
+
 			echo $args['after_widget'];
 		}
 	}
@@ -111,7 +130,7 @@
 	public function update( $new_instance, $old_instance ) {
 		$instance          = $old_instance;
 		$instance['title'] = sanitize_text_field( $new_instance['title'] );
-		if ( in_array( $new_instance['sortby'], array( 'post_title', 'menu_order', 'ID' ) ) ) {
+		if ( in_array( $new_instance['sortby'], array( 'post_title', 'menu_order', 'ID' ), true ) ) {
 			$instance['sortby'] = $new_instance['sortby'];
 		} else {
 			$instance['sortby'] = 'menu_order';
@@ -130,7 +149,7 @@
 	 * @param array $instance Current settings.
 	 */
 	public function form( $instance ) {
-		//Defaults
+		// Defaults.
 		$instance = wp_parse_args(
 			(array) $instance,
 			array(
@@ -144,6 +163,7 @@
 			<label for="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"><?php _e( 'Title:' ); ?></label>
 			<input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'title' ) ); ?>" type="text" value="<?php echo esc_attr( $instance['title'] ); ?>" />
 		</p>
+
 		<p>
 			<label for="<?php echo esc_attr( $this->get_field_id( 'sortby' ) ); ?>"><?php _e( 'Sort by:' ); ?></label>
 			<select name="<?php echo esc_attr( $this->get_field_name( 'sortby' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'sortby' ) ); ?>" class="widefat">
@@ -152,6 +172,7 @@
 				<option value="ID"<?php selected( $instance['sortby'], 'ID' ); ?>><?php _e( 'Page ID' ); ?></option>
 			</select>
 		</p>
+
 		<p>
 			<label for="<?php echo esc_attr( $this->get_field_id( 'exclude' ) ); ?>"><?php _e( 'Exclude:' ); ?></label>
 			<input type="text" value="<?php echo esc_attr( $instance['exclude'] ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'exclude' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'exclude' ) ); ?>" class="widefat" />