Throw 'SecurityError' upon cross-origin Location access.

LayoutTests/http/tests/security/xssAuditor/resources/utilities.js

 function checkIfFrameLocationMatchesSrcAndCallDone(frameId)
 {
     if (!window.testRunner)
         return;
 
-    var actualURL = 'unavailable', frame = document.getElementById(frameId); 
+    var actualURL = 'unavailable', frame = document.getElementById(frameId);
     try {
         actualURL = frame.contentWindow.location.href;
-    } 
-    catch (e) {}
-    
+    }
+    catch (e) {
+        actualURL = '[Location object access threw exception]';
+    }
+
     if (actualURL != frame.src)
-        alert('URL mismatch: ' + actualURL + ' vs. ' + frame.src);
+        alert('URL mismatch: \'' + actualURL + '\' vs. \'' + frame.src + '\'');
 
     testRunner.notifyDone();
 }
 
 function sendRequestFromIFrame(url, params, HTTPMethod, callbackWhenDone)
 {
     if (!params || !params.length)
         return;
         
     if (!HTTPMethod)
@@ skipping 29 matching lines @@
         var index = ids.indexOf(event.data);
         if (index == -1)
             return;
 
         loadAttempted = loadAttempted | (1 << index);
         if (loadAttempted == (1 << ids.length) - 1)
             testRunner.notifyDone();
     }, false);
 }