[webnfc]: Step 1: Add NavigatorNfc, Nfc and Layout tests.

Source/modules/nfc/Nfc.cpp

+// Copyright 2015 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.
+
+#include "config.h"
+#include "modules/nfc/Nfc.h"
+
+#include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "core/dom/DOMException.h"
+#include "core/dom/ExceptionCode.h"
+
+namespace blink {
+
+Nfc::Nfc(ExecutionContext* context, LocalFrame* frame)
+    : ActiveDOMObject(context)
+    , DOMWindowProperty(frame)
+{
+}
+
+Nfc::~Nfc()
+{
+}
+
+ScriptPromise Nfc::requestAdapter(ScriptState* scriptState)
+{
+    // TODO(riju): To be implemented.
+    return ScriptPromise::rejectWithDOMException(scriptState, DOMException::create(NotSupportedError));
+}
+
+DEFINE_TRACE(Nfc)
+{
+    ActiveDOMObject::trace(visitor);
+    DOMWindowProperty::trace(visitor);
+}
+
+} // namespace blink