Include <algorithm> if you use functions from <algorithm>.

third_party/WebKit/Source/core/css/PageRuleCollector.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 14 matching lines @@
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/css/PageRuleCollector.h"
 
 #include "core/css/StylePropertySet.h"
 #include "core/css/StyleRule.h"
 #include "core/css/resolver/StyleResolverState.h"
+#include <algorithm>
 
 namespace blink {
 
 static inline bool comparePageRules(const StyleRulePage* r1, const StyleRulePage* r2)
 {
     return r1->selector()->specificity() < r2->selector()->specificity();
 }
 
 bool PageRuleCollector::isLeftPage(const ComputedStyle* rootElementStyle, int pageIndex) const
 {
@@ skipping 71 matching lines @@
         const StylePropertySet& properties = rule->properties();
         if (properties.isEmpty())
             continue;
 
         // Add this rule to our list of matched rules.
         matchedRules.append(rule);
     }
 }
 
 } // namespace blink