[css-grid] mimax(auto, <flex>) should be serialized as <flex>

third_party/WebKit/Source/core/style/GridLength.h

 /*
  * 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
  * 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 58 matching lines @@
   bool operator==(const GridLength& o) const {
     return m_length == o.m_length && m_flex == o.m_flex && m_type == o.m_type;
   }
 
   bool isContentSized() const {
     return m_type == LengthType &&
            (m_length.isAuto() || m_length.isMinContent() ||
             m_length.isMaxContent());
   }
 
+  bool isAuto() const { return m_type == LengthType && m_length.isAuto(); }
+
  private:
   // Ideally we would put the 2 following fields in a union, but Length has a
   // constructor, a destructor and a copy assignment which isn't allowed.
   Length m_length;
   double m_flex;
   enum GridLengthType { LengthType, FlexType };
   GridLengthType m_type;
 };
 
 }  // namespace blink
 
 #endif  // GridLength_h