Make sure HMathMinMax always has a supported representation

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3674 matching lines @@
 
   virtual Representation RequiredInputRepresentation(int index) {
     return index == 0 ? Representation::Tagged()
                       : representation();
   }
 
   virtual Representation observed_input_representation(int index) {
     return RequiredInputRepresentation(index);
   }
 
+  virtual void InferRepresentation(HInferRepresentation* h_infer);
+
   virtual Representation RepresentationFromInputs() {
     Representation left_rep = left()->representation();
     Representation right_rep = right()->representation();
     if ((left_rep.IsNone() || left_rep.IsInteger32()) &&
         (right_rep.IsNone() || right_rep.IsInteger32())) {
       return Representation::Integer32();
     }
     return Representation::Double();
   }
 
@@ skipping 1713 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_