Don't include LayoutObject-derived headers where not needed.

third_party/WebKit/Source/core/layout/FlexibleBoxAlgorithm.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 12 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/layout/FlexibleBoxAlgorithm.h"
 
+#include "core/layout/LayoutBox.h"
+
 namespace blink {
 
 FlexItem::FlexItem(LayoutBox* box,
                    LayoutUnit flexBaseContentSize,
                    LayoutUnit hypotheticalMainContentSize,
                    LayoutUnit mainAxisBorderAndPadding,
                    LayoutUnit mainAxisMargin)
     : box(box),
       flexBaseContentSize(flexBaseContentSize),
       hypotheticalMainContentSize(hypotheticalMainContentSize),
@@ skipping 40 matching lines @@
     totalFlexShrink += flexItem.box->style()->flexShrink();
     totalWeightedFlexShrink +=
         flexItem.box->style()->flexShrink() * flexItem.flexBaseContentSize;
     sumHypotheticalMainSize += flexItem.hypotheticalMainAxisMarginBoxSize();
   }
   DCHECK(lineItems.size() > 0 || nextIndex == m_allItems.size());
   return lineItems.size() > 0;
 }
 
 }  // namespace blink