Call isValidProtocol() function first in order to remove duplicated protocol checking in NavigatorC…

LayoutTests/navigatorcontentutils/is-protocol-handler-registered.html

Index: LayoutTests/navigatorcontentutils/is-protocol-handler-registered.html
diff --git a/LayoutTests/navigatorcontentutils/is-protocol-handler-registered.html b/LayoutTests/navigatorcontentutils/is-protocol-handler-registered.html
index 3bc676b36faf623ac2b92793a0a3ffb445449f6b..c015588eb72d2f1d91f65860245c6d39fdb8fd1f 100644
--- a/LayoutTests/navigatorcontentutils/is-protocol-handler-registered.html
+++ b/LayoutTests/navigatorcontentutils/is-protocol-handler-registered.html
@@ -37,7 +37,7 @@ invalid_schemes.forEach(function (scheme) {
     try {
         window.navigator.isProtocolHandlerRegistered(scheme, 'invalid scheme uri=%s');
     } catch (e) {
-        succeeded = 'SyntaxError' == e.name;
+        succeeded = 'SecurityError' == e.name;
         errorMessage = e.message;
     }