Migrate WTF::LinkedHashSet/ListHashSet::last() to ::back()

third_party/WebKit/Source/core/layout/LayoutBlockFlow.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003-2013 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2013 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
@@ skipping 354 matching lines @@
   // |logicalTopMarginEdge| is the minimum logical top offset for the float.
   // The value returned is the minimum logical top offset for subsequent
   // floats.
   LayoutUnit positionAndLayoutFloat(FloatingObject&,
                                     LayoutUnit logicalTopMarginEdge);
 
   LayoutUnit nextFloatLogicalBottomBelow(LayoutUnit) const;
   LayoutUnit nextFloatLogicalBottomBelowForBlock(LayoutUnit) const;
 
   FloatingObject* lastFloatFromPreviousLine() const {
-    return containsFloats() ? m_floatingObjects->set().last().get() : nullptr;
+    return containsFloats() ? m_floatingObjects->set().back().get() : nullptr;
   }
 
   void setShouldDoFullPaintInvalidationForFirstLine();
 
   void simplifiedNormalFlowInlineLayout();
   bool recalcInlineChildrenOverflowAfterStyleChange();
 
   PositionWithAffinity positionForPoint(const LayoutPoint&) override;
 
   LayoutUnit lowestFloatLogicalBottom(EClear = EClear::kBoth) const;
@@ skipping 567 matching lines @@
   void positionDialog();
 
   // END METHODS DEFINED IN LayoutBlockFlowLine
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBlockFlow, isLayoutBlockFlow());
 
 }  // namespace blink
 
 #endif  // LayoutBlockFlow_h