Improve SecurityError message on verifyProtocolHandlerScheme()

LayoutTests/fast/dom/register-protocol-handler.html

Index: LayoutTests/fast/dom/register-protocol-handler.html
diff --git a/LayoutTests/fast/dom/register-protocol-handler.html b/LayoutTests/fast/dom/register-protocol-handler.html
index edd02f9aad6df55e27529fd4da22acd8d579de94..6b9c5cb0aba64aaf7055be17aec37356a7008013 100644
--- a/LayoutTests/fast/dom/register-protocol-handler.html
+++ b/LayoutTests/fast/dom/register-protocol-handler.html
@@ -20,15 +20,17 @@ else
 var invalid_protocols = ['http', 'https', 'file', 'web+'];
 invalid_protocols.forEach(function (protocol) {
     var succeeded = false;
+    var errorMessage;
     try {
         window.navigator.registerProtocolHandler(protocol, "invalid protocol %s", "title");
     } catch (e) {
         succeeded = 'SecurityError' == e.name;
+        errorMessage = e.message;
     }
 
-    if (succeeded)
-        debug('Pass: Invalid protocol "' + protocol + '" threw SecurityError exception.');
-    else
+    if (succeeded) {
+        debug('Pass: Invalid protocol "' + protocol + '" threw SecurityError exception: "' + errorMessage + '".');
+    }else
         debug('Fail: Invalid protocol "' + protocol + '" allowed.');
 });