IDL: Simplify [TypeChecking=Interface] code generation

Source/bindings/tests/results/modules/V8TestInterface5.cpp

Index: Source/bindings/tests/results/modules/V8TestInterface5.cpp
diff --git a/Source/bindings/tests/results/modules/V8TestInterface5.cpp b/Source/bindings/tests/results/modules/V8TestInterface5.cpp
index 79a88892eeade0fd4104a6e0663e5c30312cb0f6..ee823a87929ce68f02d54fd440ef1c0f200bc7d7 100644
--- a/Source/bindings/tests/results/modules/V8TestInterface5.cpp
+++ b/Source/bindings/tests/results/modules/V8TestInterface5.cpp
@@ -52,13 +52,13 @@ static void testInterfaceAttributeAttributeSetter(v8::Local<v8::Value> v8Value,
 {
     v8::Handle<v8::Object> holder = info.Holder();
     ExceptionState exceptionState(ExceptionState::SetterContext, "testInterfaceAttribute", "TestInterface5", holder, info.GetIsolate());
-    if (!V8TestInterface5::hasInstance(v8Value, info.GetIsolate())) {
+    TestInterface5Implementation* impl = V8TestInterface5::toImpl(holder);
+    TestInterface5Implementation* cppValue = V8TestInterface5::toImplWithTypeCheck(info.GetIsolate(), v8Value);
+    if (!cppValue) {
         exceptionState.throwTypeError("The provided value is not of type 'TestInterface5'.");
         exceptionState.throwIfNeeded();
         return;
     }
-    TestInterface5Implementation* impl = V8TestInterface5::toImpl(holder);
-    TestInterface5Implementation* cppValue = V8TestInterface5::toImpl(v8::Handle<v8::Object>::Cast(v8Value));
     impl->setTestInterfaceAttribute(WTF::getPtr(cppValue));
 }
 
@@ -344,11 +344,11 @@ static void voidMethodTestInterfaceEmptyArgMethod(const v8::FunctionCallbackInfo
     TestInterface5Implementation* impl = V8TestInterface5::toImpl(info.Holder());
     TestInterfaceEmpty* testInterfaceEmptyArg;
     {
-        if (info.Length() > 0 && !V8TestInterfaceEmpty::hasInstance(info[0], info.GetIsolate())) {
+        testInterfaceEmptyArg = V8TestInterfaceEmpty::toImplWithTypeCheck(info.GetIsolate(), info[0]);
+        if (!testInterfaceEmptyArg) {
             V8ThrowException::throwTypeError(info.GetIsolate(), ExceptionMessages::failedToExecute("voidMethodTestInterfaceEmptyArg", "TestInterface5", "parameter 1 is not of type 'TestInterfaceEmpty'."));
             return;
         }
-        testInterfaceEmptyArg = V8TestInterfaceEmpty::toImpl(v8::Handle<v8::Object>::Cast(info[0]));
     }
     impl->voidMethodTestInterfaceEmptyArg(testInterfaceEmptyArg);
 }