Twenty Twenty: Fix post navigation to respect sort order.

Change the labels on post navigation links when the sort order is changed so the labels accurately reflect the target entries.

Previously, if the sort order was reversed, 'Older' or 'Previous' links would navigate to newer entries and 'Newer' or 'Next' links would navigate to older entries.

Props jikamens, dancameron, obenland, shrey0shrivastava, sirlouen, sabernhardt, shailu25, joedolson.
See WordPress#10219.

git-svn-id: https://develop.svn.wordpress.org/trunk@61092 602fd350-edb4-49c9-b593-d223f7449a82

Author: joedolson

src/wp-content/themes/twentytwenty/template-parts/pagination.php

@@ -9,22 +9,28 @@
  * @since Twenty Twenty 1.0
  */
 
+$order = get_query_var( 'order', 'DESC' );
+
+/*
+ * Translators: This text contains HTML to allow the text to be shorter on small screens.
+ * The text inside the span with the class nav-short will be hidden on small screens.
+ */
+$new_posts_text = __( 'Newer <span class="nav-short">Posts</span>', 'twentytwenty' );
+
+/*
+ * Translators: This text contains HTML to allow the text to be shorter on small screens.
+ * The text inside the span with the class nav-short will be hidden on small screens.
+ */
+$old_posts_text = __( 'Older <span class="nav-short">Posts</span>', 'twentytwenty' );
+
 $prev_text = sprintf(
 	'%s <span class="nav-prev-text">%s</span>',
 	'<span aria-hidden="true">&larr;</span>',
-	/*
-	 * Translators: This text contains HTML to allow the text to be shorter on small screens.
-	 * The text inside the span with the class nav-short will be hidden on small screens.
-	 */
-	__( 'Newer <span class="nav-short">Posts</span>', 'twentytwenty' )
+	( 'DESC' === $order ) ? $new_posts_text : $old_posts_text
 );
 $next_text = sprintf(
 	'<span class="nav-next-text">%s</span> %s',
-	/*
-	 * Translators: This text contains HTML to allow the text to be shorter on small screens.
-	 * The text inside the span with the class nav-short will be hidden on small screens.
-	 */
-	__( 'Older <span class="nav-short">Posts</span>', 'twentytwenty' ),
+	( 'DESC' === $order ) ? $old_posts_text : $new_posts_text,
 	'<span aria-hidden="true">&rarr;</span>'
 );