Coding Standards: Use more meaningful variable names in Theme Editor.

Per the [https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#naming-conventions Naming Conventions]:

> Don’t abbreviate variable names unnecessarily; let the code be unambiguous and self-documenting.

Follow-up to [41721], [60928].

See #63168.

git-svn-id: https://develop.svn.wordpress.org/trunk@60932 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/theme-editor.php

@@ -121,9 +121,11 @@
 $posted_content = null;
 
 if ( 'POST' === $_SERVER['REQUEST_METHOD'] ) {
-	$r = wp_edit_theme_plugin_file( wp_unslash( $_POST ) );
-	if ( is_wp_error( $r ) ) {
-		$edit_error = $r;
+	$edit_result = wp_edit_theme_plugin_file( wp_unslash( $_POST ) );
+
+	if ( is_wp_error( $edit_result ) ) {
+		$edit_error = $edit_result;
+
 		if ( check_ajax_referer( 'edit-theme_' . $stylesheet . '_' . $relative_file, 'nonce', false ) && isset( $_POST['newcontent'] ) ) {
 			$posted_content = wp_unslash( $_POST['newcontent'] );
 		}