Improve precision of error messages from failed CORS checks.

LayoutTests/http/tests/xmlhttprequest/resources/access-control-allow-lists.php

 <?php
 
-$origin = $_GET['origin'];
-
-if ($origin != 'none')
-    header("Access-Control-Allow-Origin: $origin");
+if (isset($_GET['origin'])) {
+    header("Access-Control-Allow-Origin: " . $_GET['origin']);
+} else if (isset($_GET['origins'])) {
+    $origins = explode(',', $_GET['origins']);
+    for ($i = 0; $i < sizeof($origins); ++$i)
+         header("Access-Control-Allow-Origin: " . $origins[$i], false);
+}
 
 if (isset($_GET['headers']))
     header("Access-Control-Allow-Headers: {$_GET['headers']}");
 if (isset($_GET['methods']))
     header("Access-Control-Allow-Methods: {$_GET['methods']}");
 
 foreach ($_SERVER as $name => $value)
 {
     if (substr($name, 0, 5) == 'HTTP_')
     {
         $name = strtolower(str_replace('_', '-', substr($name, 5)));
         $headers[$name] = $value;
     } else if ($name == "CONTENT_TYPE") {
         $headers["content-type"] = $value;
     } else if ($name == "CONTENT_LENGTH") {
         $headers["content-length"] = $value;
     }
 }
 
 $headers['get_value'] = isset($_GET['get_value']) ? $_GET['get_value'] : '';
 
 echo json_encode( $headers );