[LayoutNG] Introduce NGPhysicalFragment and make NGFragment a 'view'

third_party/WebKit/Source/core/layout/ng/ng_direction.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_direction.h"
+
+#include "platform/text/TextDirection.h"
+#include "wtf/Assertions.h"
+
+namespace blink {
+
+NGDirection FromPlatformDirection(TextDirection direction) {
+  switch (direction) {
+    case LTR:
+      return LeftToRight;
+    case RTL:
+      return RightToLeft;
+    default:
+      NOTREACHED();
+      return LeftToRight;
+  }
+}
+
+}  // namespace blink