Remove deprecated window.showModalDialog()

LayoutTests/http/tests/security/cross-frame-access-put.html

 
 <p>This test checks cross-frame access security of window attribute setters (rdar://problem/5326791).</p>
 <iframe src="http://localhost:8000/security/resources/cross-frame-iframe-for-put-test.html" style=""></iframe>
 <pre id="console"></pre>
 <script>
 function log(s)
 {
     document.getElementById("console").appendChild(document.createTextNode(s + "\n"));
 }
 
@@ skipping 205 matching lines @@
     setForbiddenProperty(targetWindow, "prompt");
     setForbiddenProperty(targetWindow, "releaseEvents");
     setForbiddenProperty(targetWindow, "removeEventListener");
     setForbiddenProperty(targetWindow, "resizeBy");
     setForbiddenProperty(targetWindow, "resizeTo");
     setForbiddenProperty(targetWindow, "scroll");
     setForbiddenProperty(targetWindow, "scrollBy");
     setForbiddenProperty(targetWindow, "scrollTo");
     setForbiddenProperty(targetWindow, "setInterval");
     setForbiddenProperty(targetWindow, "setTimeout");
-    setForbiddenProperty(targetWindow, "showModalDialog");
     setForbiddenProperty(targetWindow, "stop");
 
     setTimeout(function() {
         // log(targetWindow.focus.__proto__);
         log("MAIN WINDOW: !!-- Test ended--!!");
 
         window.stop();
 
         if (window.testRunner)
             testRunner.notifyDone();
     }, 1);
 }
 </script>