[Layout API] Use layoutViewItem() in Document

third_party/WebKit/Source/core/layout/api/LayoutBlockItem.h

 
 // 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.
 
 #ifndef LayoutBlockItem_h
 #define LayoutBlockItem_h
 
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/api/LayoutBoxItem.h"
@@ skipping 20 matching lines @@
     void invalidatePaintRectangle(const LayoutRect& layoutRect) const
     {
         toBlock()->invalidatePaintRectangle(layoutRect);
     }
 
     bool recalcOverflowAfterStyleChange()
     {
         return toBlock()->recalcOverflowAfterStyleChange();
     }
 
+    LayoutItem firstChild() const
+    {
+        return LayoutItem(toBlock()->firstChild());
+    }
+
 private:
     LayoutBlock* toBlock() { return toLayoutBlock(layoutObject()); }
     const LayoutBlock* toBlock() const { return toLayoutBlock(layoutObject()); }
 };
 
 } // namespace blink
 
 #endif // LayoutBlockItem_h