[LayoutNG] Initial version of NGBox wrapper object.

third_party/WebKit/Source/core/layout/ng/ng_box.cc

+// Copyright 2016 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 "core/layout/ng/ng_box.h"
+
+#include "core/layout/LayoutObject.h"
+#include "core/layout/ng/ng_block_layout_algorithm.h"
+
+namespace blink {
+
+NGFragment* NGBox::layout(const NGConstraintSpace& constraintSpace) {
+  NGBlockLayoutAlgorithm algorithm(style(), firstChild());
+  return algorithm.layout(constraintSpace);
+}
+
+const ComputedStyle* NGBox::style() const {
+  return m_layoutObject->style();
+}
+
+const NGBox NGBox::firstChild() const {
+  return NGBox(m_layoutObject->slowFirstChild());
+}
+
+const NGBox NGBox::nextSibling() const {
+  return NGBox(m_layoutObject->nextSibling());
+}
+
+}  // namespace blink