IDL: Support optional argument default value syntax

Source/bindings/tests/results/V8TestInterfaceConstructor2.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file has been auto-generated by code_generator_v8.py. DO NOT MODIFY!
 
 #include "config.h"
 #include "V8TestInterfaceConstructor2.h"
 
 #include "RuntimeEnabledFeatures.h"
@@ skipping 77 matching lines @@
     V8StringResource<> defaultUndefinedOptionalStringArg;
     V8StringResource<> defaultNullStringOptionalStringArg;
     Dictionary defaultUndefinedOptionalDictionaryArg;
     V8StringResource<> optionalStringArg;
     {
         v8::TryCatch block;
         V8RethrowTryCatchScope rethrow(block);
         TONATIVE_VOID_INTERNAL(testInterfaceEmptyArg, V8TestInterfaceEmpty::toNativeWithTypeCheck(info.GetIsolate(), info[0]));
         TONATIVE_VOID_EXCEPTIONSTATE_INTERNAL(longArg, toInt32(info[1], exceptionState), exceptionState);
         TOSTRING_VOID_INTERNAL(defaultUndefinedOptionalStringArg, info[2]);
-        TOSTRING_VOID_INTERNAL(defaultNullStringOptionalStringArg, argumentOrNull(info, 3));
+        if (info.Length() > 3) {
+            TOSTRING_VOID_INTERNAL(defaultNullStringOptionalStringArg, info[3]);
+        } else {
+            defaultNullStringOptionalStringArg = String();
+        }
         TONATIVE_VOID_INTERNAL(defaultUndefinedOptionalDictionaryArg, Dictionary(info[4], info.GetIsolate()));
         if (!defaultUndefinedOptionalDictionaryArg.isUndefinedOrNull() && !defaultUndefinedOptionalDictionaryArg.isObject()) {
             exceptionState.throwTypeError("parameter 5 ('defaultUndefinedOptionalDictionaryArg') is not an object.");
             exceptionState.throwIfNeeded();
             return;
         }
         if (UNLIKELY(info.Length() <= 5)) {
             RefPtr<TestInterfaceConstructor2> impl = TestInterfaceConstructor2::create(testInterfaceEmptyArg, longArg, defaultUndefinedOptionalStringArg, defaultNullStringOptionalStringArg, defaultUndefinedOptionalDictionaryArg);
             v8::Handle<v8::Object> wrapper = info.Holder();
             V8DOMWrapper::associateObjectWithWrapper<V8TestInterfaceConstructor2>(impl.release(), &V8TestInterfaceConstructor2::wrapperTypeInfo, wrapper, isolate, WrapperConfiguration::Independent);
@@ skipping 154 matching lines @@
     fromInternalPointer(object)->deref();
 }
 
 template<>
 v8::Handle<v8::Value> toV8NoInline(TestInterfaceConstructor2* impl, v8::Handle<v8::Object> creationContext, v8::Isolate* isolate)
 {
     return toV8(impl, creationContext, isolate);
 }
 
 } // namespace WebCore