Coding Standards: Use more meaningful variable names in Plugin 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 [10879], [41721].

Props costdev, mukesh27.
See #63168.

git-svn-id: https://develop.svn.wordpress.org/trunk@60928 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/plugin-editor.php

@@ -93,9 +93,11 @@
 $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-plugin_' . $file, 'nonce', false ) && isset( $_POST['newcontent'] ) ) {
 			$posted_content = wp_unslash( $_POST['newcontent'] );
 		}
@@ -122,9 +124,10 @@
 } else {
 	// Get the extension of the file.
 	if ( preg_match( '/\.([^.]+)$/', $real_file, $matches ) ) {
-		$ext = strtolower( $matches[1] );
+		$extension = strtolower( $matches[1] );
+
 		// If extension is not in the acceptable list, skip it.
-		if ( ! in_array( $ext, $editable_extensions, true ) ) {
+		if ( ! in_array( $extension, $editable_extensions, true ) ) {
 			wp_die( sprintf( '<p>%s</p>', __( 'Files of this type are not editable.' ) ) );
 		}
 	}