Encapsulate optional SerializedScriptValue serialize/deserialize parameters.

third_party/WebKit/Source/web/tests/WebFrameTest.cpp

Index: third_party/WebKit/Source/web/tests/WebFrameTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/WebFrameTest.cpp b/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
index 28af54158677b611b6dac0044c729a413d2943f7..c806ccf5bb2817eaa64aadf0cb45cbf50f1595bb 100644
--- a/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
+++ b/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
@@ -1006,7 +1006,7 @@ RefPtr<SerializedScriptValue> serializeString(const StringView& message,
   ScriptState::Scope scope(scriptState);
   V8ScriptValueSerializer serializer(scriptState);
   return serializer.serialize(v8String(scriptState->isolate(), message),
-                              nullptr, exceptionState);
+                              exceptionState);
 }
 
 }  // namespace