bindings: Throw a type error if converting an interface or callback function fails.

third_party/WebKit/Source/bindings/tests/results/modules/V8TestInterface5.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!
 
 // This file has been generated from the Jinja2 template in
 // third_party/WebKit/Source/bindings/templates/interface.cpp.tmpl
 
@@ skipping 860 matching lines @@
 
 v8::Local<v8::Object> V8TestInterface5::findInstanceInPrototypeChain(v8::Local<v8::Value> v8Value, v8::Isolate* isolate) {
   return V8PerIsolateData::from(isolate)->findInstanceInPrototypeChain(&wrapperTypeInfo, v8Value);
 }
 
 TestInterface5Implementation* V8TestInterface5::toImplWithTypeCheck(v8::Isolate* isolate, v8::Local<v8::Value> value) {
   return hasInstance(value, isolate) ? toImpl(v8::Local<v8::Object>::Cast(value)) : nullptr;
 }
 
 TestInterface5Implementation* NativeValueTraits<TestInterface5Implementation>::nativeValue(v8::Isolate* isolate, v8::Local<v8::Value> value, ExceptionState& exceptionState) {
-  return V8TestInterface5::toImplWithTypeCheck(isolate, value);
+  TestInterface5Implementation* nativeValue = V8TestInterface5::toImplWithTypeCheck(isolate, value);
+  if (!nativeValue)
+    exceptionState.throwTypeError("Unable to convert value to TestInterface5.");
+  return nativeValue;
 }
 
 void V8TestInterface5::preparePrototypeAndInterfaceObject(v8::Local<v8::Context> context, const DOMWrapperWorld& world, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate) {
   v8::Isolate* isolate = context->GetIsolate();
   v8::Local<v8::Signature> signature = v8::Signature::New(isolate, interfaceTemplate);
   ExecutionContext* executionContext = toExecutionContext(context);
   DCHECK(executionContext);
 
   if (executionContext && (executionContext->isWorkerGlobalScope())) {
     static const V8DOMConfiguration::AccessorConfiguration accessorConfiguration[] = {
@@ skipping 40 matching lines @@
   if (executionContext && (executionContext->isDocument() || executionContext->isServiceWorkerGlobalScope())) {
     const V8DOMConfiguration::MethodConfiguration windowAndServiceWorkerExposedMethodMethodConfiguration[] = {
       {"windowAndServiceWorkerExposedMethod", V8TestInterface5::windowAndServiceWorkerExposedMethodMethodCallback, 0, v8::None, V8DOMConfiguration::OnPrototype, V8DOMConfiguration::CheckHolder, V8DOMConfiguration::DoNotCheckAccess, V8DOMConfiguration::AllWorlds}
     };
     for (const auto& methodConfig : windowAndServiceWorkerExposedMethodMethodConfiguration)
       V8DOMConfiguration::installMethod(isolate, world, v8::Local<v8::Object>(), prototypeObject, interfaceObject, signature, methodConfig);
   }
 }
 
 }  // namespace blink