Make window.screen property non replaceable

LayoutTests/fast/dom/Window/get-set-properties.html

 <p>This page tests getting and setting window properties and functions.</p>
 <pre id="console"></pre>
 
 <script>
 function log(s)
 {
     document.getElementById("console").appendChild(document.createTextNode(s + "\n"));
 }
 
 function shouldBe(a, b)
@@ skipping 197 matching lines @@
     "toolbar"
 ];
 
 var windowReadOnlyProperties = [
     "closed",
     "document",
     "history",
     "navigator",
     "pageXOffset",
     "pageYOffset",
+    "screen",
     "window",
     "top"
 ];
 
 var windowReadWriteStringProperties = [
     "defaultStatus",
     "defaultstatus",
     "name",
     "status"
 ];
@@ skipping 91 matching lines @@
 
     log("\n----- tests for getting/setting event handlers -----\n");
 
     for (var i = 0; i < windowEventHandlers.length; i++) {
         var property = windowEventHandlers[i];
         shouldBeTrue("canGet('" + property + "')");
         shouldBeTrue("canSetWithCallable('" + property + "')");
     }
 }
 </script>