Create LineLayout api

Source/core/layout/api/LineLayoutInline.cpp

Index: Source/core/layout/api/LineLayoutInline.cpp
diff --git a/Source/core/layout/api/LineLayoutInline.cpp b/Source/core/layout/api/LineLayoutInline.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..417b357903b8a31cb532923f1c42eff1fe366816
--- /dev/null
+++ b/Source/core/layout/api/LineLayoutInline.cpp
@@ -0,0 +1,43 @@
+// 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 "core/layout/api/LineLayoutInline.h"
+
+#include "core/layout/LayoutInline.h"
+
+namespace blink {
+
+LineLayoutInline::LineLayoutInline(LayoutInline* layoutInline)
+    : LineLayoutItem(layoutInline)
+{
+}
+
+LineLayoutInline::LineLayoutInline(const LineLayoutItem& item)
+    : LineLayoutItem(item)
+{
+    ASSERT(!item.layoutObject() || item.layoutObject()->isInline());
+}
+
+LineLayoutItem LineLayoutInline::firstChild() const
+{
+    return toInline()->firstChild();
+}
+
+LineLayoutItem LineLayoutInline::lastChild() const
+{
+    return toInline()->lastChild();
+}
+
+LayoutInline* LineLayoutInline::toInline()
+{
+    return toLayoutInline(layoutObject());
+}
+
+const LayoutInline* LineLayoutInline::toInline() const
+{
+    return toLayoutInline(layoutObject());
+}
+
+} // namespace blink