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

Source/modules/nfc/NavigatorNFC.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/NavigatorNFC.h"
+
+#include "core/frame/Navigator.h"
+#include "modules/nfc/NFC.h"
+
+namespace blink {
+
+NavigatorNFC::NavigatorNFC()
+{
+}
+
+const char* NavigatorNFC::supplementName()
+{
+    return "NavigatorNFC";
+}
+
+NavigatorNFC& NavigatorNFC::from(Navigator& navigator)
+{
+    NavigatorNFC* supplement = static_cast<NavigatorNFC*>(HeapSupplement<Navigator>::from(navigator, supplementName()));
+    if (!supplement) {
+        supplement = new NavigatorNFC();
+        provideTo(navigator, supplementName(), supplement);
+    }
+    return *supplement;
+}
+
+NFC* NavigatorNFC::nfc(ExecutionContext* context, Navigator& navigator)
+{
+    NavigatorNFC& self = NavigatorNFC::from(navigator);
+    if (!self.m_nfc) {
+        if (!navigator.frame())
+            return nullptr;
+        self.m_nfc = NFC::create(context, navigator.frame());
+    }
+    return self.m_nfc.get();
+}
+
+DEFINE_TRACE(NavigatorNFC)
+{
+    visitor->trace(m_nfc);
+    HeapSupplement<Navigator>::trace(visitor);
+}
+
+} // namespace blink