Cleanup dart to string conversions.

Source/WebCore/bindings/dart/custom/DartWebSocketCustom.cpp

 // Copyright 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 34 matching lines @@
 {
     DartApiScope dartApiScope;
     Dart_Handle exception = 0;
     {
         ScriptExecutionContext* context = DartUtilities::scriptExecutionContext();
         if (!context) {
             exception = Dart_NewString("WebSocket constructor's associated context is not available");
             goto fail;
         }
 
-        const ParameterAdapter<String> url(Dart_GetNativeArgument(args, 0));
-        if (!url.conversionSuccessful()) {
-            exception = url.exception();
+        DartStringAdapter url = DartUtilities::dartToString(Dart_GetNativeArgument(args, 0), exception);
+        if (exception)
             goto fail;
-        }
 
         const KURL& absoluteURL = context->completeURL(url);
 
         RefPtr<WebSocket> receiver = WebSocket::create(context);
         ExceptionCode ec = 0;
         receiver->connect(absoluteURL, ec);
         if (UNLIKELY(ec)) {
             exception = DartDOMWrapper::exceptionCodeToDartException(ec);
             goto fail;
         }
@@ skipping 22 matching lines @@
             ArrayBuffer* data = DartArrayBuffer::toNative(dataHandle, exception);
             if (exception)
                 goto fail;
             result = receiver->send(data, ec);
         } else if (DartDOMWrapper::instanceOf<DartBlob>(dataHandle)) {
             Blob* data = DartBlob::toNative(dataHandle, exception);
             if (exception)
                 goto fail;
             result = receiver->send(data, ec);
         } else if (Dart_IsString(dataHandle)) {
-            const ParameterAdapter<String> data(dataHandle);
-            if (!data.conversionSuccessful()) {
-                exception = data.exception();
+            DartStringAdapter data = DartUtilities::dartToString(dataHandle, exception);
+            if (exception)
                 goto fail;
-            }
             result = receiver->send(data, ec);
         } else {
             exception = Dart_NewString("Unsupported data argument type");
             goto fail;
         }
 
         if (UNLIKELY(ec)) {
             exception = DartDOMWrapper::exceptionCodeToDartException(ec);
             goto fail;
         }
@@ skipping 27 matching lines @@
 fail:
     Dart_ThrowException(exception);
     ASSERT_NOT_REACHED();
 }
 
 }
 
 }
 
 #endif // ENABLE(WEB_SOCKETS)