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

third_party/WebKit/Source/wtf/text/StringBuilder.cpp

 /*
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2012 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 12 matching lines @@
  * (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 "config.h"
 #include "StringBuilder.h"
 
 #include "IntegerToStringConversion.h"
 #include "WTFString.h"
 #include "wtf/dtoa.h"
+#include <algorithm>
 
 namespace WTF {
 
 static unsigned expandedCapacity(unsigned capacity, unsigned requiredLength)
 {
     static const unsigned minimumCapacity = 16;
     return std::max(requiredLength, std::max(minimumCapacity, capacity * 2));
 }
 
 void StringBuilder::reifyString()
@@ skipping 333 matching lines @@
     if (!canShrink())
         return;
     if (m_is8Bit)
         reallocateBuffer<LChar>(m_length);
     else
         reallocateBuffer<UChar>(m_length);
     m_string = m_buffer.release();
 }
 
 } // namespace WTF