IDL compiler: move EventHandler null check out of generated bindings

Source/bindings/scripts/code_generator_v8.pm

 # Copyright (C) 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
 # Copyright (C) 2006 Anders Carlsson <andersca@mac.com>
 # Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
 # Copyright (C) 2006 Alexey Proskuryakov <ap@webkit.org>
 # Copyright (C) 2006 Apple Computer, Inc.
 # Copyright (C) 2007, 2008, 2009, 2012 Google Inc.
 # Copyright (C) 2009 Cameron McCormack <cam@mcc.id.au>
 # Copyright (C) Research In Motion Limited 2010. All rights reserved.
 # Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
 # Copyright (C) 2012 Ericsson AB. All rights reserved.
@@ skipping 1937 matching lines @@
     my $useExceptions = 1 if $attribute->extendedAttributes->{"SetterRaisesException"} ||  $attribute->extendedAttributes->{"RaisesException"};
 
     if ($useExceptions) {
         AddToImplIncludes("bindings/v8/ExceptionMessages.h");
         AddToImplIncludes("bindings/v8/ExceptionState.h");
         $code .= "    ExceptionState es(info.GetIsolate());\n";
     }
 
     if ($attribute->type eq "EventHandler") {
         my $implSetterFunctionName = FirstLetterToUpperCase($attrName);
-        # Non callable input should be treated as null
-        $code .= "    if (!jsValue->IsNull() && !jsValue->IsFunction())\n";
-        $code .= "        jsValue = v8::Null(info.GetIsolate());\n";
         if (!InheritsInterface($interface, "Node")) {
             my $attrImplName = GetImplName($attribute);
             $code .= "    transferHiddenDependency(info.Holder(), imp->${attrImplName}(isolatedWorldForIsolate(info.GetIsolate())), jsValue, ${v8ClassName}::eventListenerCacheIndex, info.GetIsolate());\n";
         }
         if (($interfaceName eq "Window" or $interfaceName eq "WorkerGlobalScope") and $attribute->name eq "onerror") {
             AddToImplIncludes("bindings/v8/V8ErrorHandler.h");
             $code .= "    imp->set$implSetterFunctionName(V8EventListenerList::findOrCreateWrapper<V8ErrorHandler>(jsValue, true, info.GetIsolate()), isolatedWorldForIsolate(info.GetIsolate()));\n";
         } else {
             $code .= "    imp->set$implSetterFunctionName(V8EventListenerList::getEventListener(jsValue, true, ListenerFindOrCreate), isolatedWorldForIsolate(info.GetIsolate()));\n";
         }
@@ skipping 4226 matching lines @@
     my $interface = shift;
 
     return 1 if $interface->extendedAttributes->{"CustomToV8"};
     return 1 if $interface->extendedAttributes->{"SpecialWrapFor"};
     return 1 if InheritsInterface($interface, "Document");
 
     return 0;
 }
 
 1;