Generate a bit less code to handle failed arity checks.

Source/bindings/v8/custom/V8MutationObserverCustom.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "V8MutationObserver.h"
 
 #include "bindings/v8/ExceptionMessages.h"
+#include "bindings/v8/ExceptionState.h"
 #include "bindings/v8/V8Binding.h"
 #include "bindings/v8/V8DOMWrapper.h"
 #include "bindings/v8/V8MutationCallback.h"
 #include "bindings/v8/V8Utilities.h"
 #include "core/dom/MutationObserver.h"
 
 namespace WebCore {
 
 void V8MutationObserver::constructorCustom(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
+    ExceptionState exceptionState(ExceptionState::ConstructionContext, "MutationObserver", info.Holder(), info.GetIsolate());
     if (info.Length() < 1) {
-        throwTypeError(ExceptionMessages::failedToConstruct("MutationObserver", ExceptionMessages::notEnoughArguments(1, info.Length())), info.GetIsolate());
+        exceptionState.throwTypeError(ExceptionMessages::notEnoughArguments(1, info.Length()));
+        exceptionState.throwIfNeeded();
         return;
     }
 
     v8::Local<v8::Value> arg = info[0];
     if (!arg->IsFunction()) {
-        throwTypeError("Callback argument must be a function", info.GetIsolate());
+        exceptionState.throwTypeError("Callback argument must be a function");
+        exceptionState.throwIfNeeded();
         return;
     }
 
     ExecutionContext* context = getExecutionContext();
     v8::Handle<v8::Object> wrapper = info.Holder();
 
     OwnPtr<MutationCallback> callback = V8MutationCallback::create(v8::Handle<v8::Function>::Cast(arg), context, wrapper, info.GetIsolate());
     RefPtr<MutationObserver> observer = MutationObserver::create(callback.release());
 
     V8DOMWrapper::associateObjectWithWrapper<V8MutationObserver>(observer.release(), &wrapperTypeInfo, wrapper, info.GetIsolate(), WrapperConfiguration::Dependent);
     info.GetReturnValue().Set(wrapper);
 }
 
 } // namespace WebCore