[LayoutNG] Add NGLineBoxFragment

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

+// Copyright 2017 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_physical_line_box_fragment.h"
+
+#include "core/layout/ng/ng_floating_object.h"
+
+namespace blink {
+
+NGPhysicalLineBoxFragment::NGPhysicalLineBoxFragment(
+    NGPhysicalSize size,
+    Vector<RefPtr<NGPhysicalFragment>>& children,
+    const NGLineHeightMetrics& metrics,
+    RefPtr<NGBreakToken> break_token)
+    : NGPhysicalFragment(nullptr,
+                         size,
+                         kFragmentLineBox,
+                         std::move(break_token)),
+      metrics_(metrics) {
+  children_.swap(children);
+}
+
+}  // namespace blink