IDL: Add build target for IDL dictionary impl generation in core

Source/bindings/tests/results/V8TestObject.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 "V8TestObject.h"
 
 #include "bindings/core/v8/BindingSecurity.h"
@@ skipping 8172 matching lines @@
     impl->overloadedMethodJ(stringArg);
 }
 
 static void overloadedMethodJ2Method(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
     TestObject* impl = V8TestObject::toNative(info.Holder());
     TestDictionary* testDictionaryArg;
     {
         v8::TryCatch block;
         V8RethrowTryCatchScope rethrow(block);
-        TONATIVE_VOID_INTERNAL(testDictionaryArg, V8TestDictionary::toNative(info.GetIsolate(), info[0]));
+        if (!info[0]->IsUndefined()) {
+            TONATIVE_VOID_INTERNAL(testDictionaryArg, V8TestDictionary::toNative(info.GetIsolate(), info[0]));
+        } else {
+            testDictionaryArg = TestDictionary::create();
+        }
     }
     impl->overloadedMethodJ(testDictionaryArg);
 }
 
 static void overloadedMethodJMethod(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
     ExceptionState exceptionState(ExceptionState::ExecutionContext, "overloadedMethodJ", "TestObject", info.Holder(), info.GetIsolate());
     switch (std::min(1, info.Length())) {
     case 1:
         if (info[0]->IsObject()) {
@@ skipping 3124 matching lines @@
             // FIXME: We should support more exceptions.
             RELEASE_ASSERT_NOT_REACHED();
         }
         block.ReThrow();
         return false;
     }
     return true;
 }
 
 } // namespace blink