Create LineLayout api

Source/core/layout/api/LineLayoutInline.h

Index: Source/core/layout/api/LineLayoutInline.h
diff --git a/Source/core/layout/api/LineLayoutInline.h b/Source/core/layout/api/LineLayoutInline.h
new file mode 100644
index 0000000000000000000000000000000000000000..5221557a03cf2eeadbf203a1757a035aed3cbfc0
--- /dev/null
+++ b/Source/core/layout/api/LineLayoutInline.h
@@ -0,0 +1,58 @@
+// 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.
+
+#ifndef LineLayoutInline_h
+#define LineLayoutInline_h
+
+#include "core/layout/LayoutInline.h"
+#include "core/layout/api/LineLayoutItem.h"
+#include "platform/LayoutUnit.h"
+
+namespace blink {
+
+class ComputedStyle;
+class LayoutInline;
+class LayoutObject;
+
+class LineLayoutInline : public LineLayoutItem {
+public:
+    explicit LineLayoutInline(LayoutInline* layoutInline)
+        : LineLayoutItem(layoutInline)
+    {
+    }
+
+    LineLayoutInline(const LineLayoutItem& item)
+        : LineLayoutItem(item)
+    {
+        ASSERT(!item || item.isLayoutInline());
+    }
+
+    LineLayoutInline() { }
+
+    LineLayoutItem firstChild() const
+    {
+        return LineLayoutItem(toInline()->firstChild());
+    }
+
+    LineLayoutItem lastChild() const
+    {
+        return LineLayoutItem(toInline()->lastChild());
+    }
+
+protected:
+    LayoutInline* toInline()
+    {
+        return toLayoutInline(layoutObject());
+    }
+
+    const LayoutInline* toInline() const
+    {
+        return toLayoutInline(layoutObject());
+    }
+
+};
+
+} // namespace blink
+
+#endif // LineLayoutInline_h