Added preloader support for sizes based RW values

LayoutTests/http/tests/misc/resources/image-checks-for-rw.php

Index: LayoutTests/http/tests/misc/resources/image-checks-for-rw.php
diff --git a/LayoutTests/http/tests/misc/resources/image-checks-for-rw.php b/LayoutTests/http/tests/misc/resources/image-checks-for-rw.php
index b63367d51dfd877d100b9a3322438acb0f2ceb89..8316d66ef7267541b014cfdb3fa97cc82259a316 100644
--- a/LayoutTests/http/tests/misc/resources/image-checks-for-rw.php
+++ b/LayoutTests/http/tests/misc/resources/image-checks-for-rw.php
@@ -1,7 +1,8 @@
 <?php
     $rw = $_SERVER["HTTP_RW"];
+    $expected_rw = $_GET["rw"];
 
-    if($rw) {
+    if($rw == $expected_rw) {
         $fn = fopen("compass.jpg", "r");
         fpassthru($fn);
         fclose($fn);