Correctly set kCanBeDivByZero flag for HMathFloorOfDiv.

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 3093 matching lines @@
 };
 
 
 class HMathFloorOfDiv: public HBinaryOperation {
  public:
   HMathFloorOfDiv(HValue* context, HValue* left, HValue* right)
       : HBinaryOperation(context, left, right) {
     set_representation(Representation::Integer32());
     SetFlag(kUseGVN);
     SetFlag(kCanOverflow);
+    if (!right->IsConstant()) {
+      SetFlag(kCanBeDivByZero);
+    }
   }
 
   virtual HValue* EnsureAndPropagateNotMinusZero(BitVector* visited);
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Integer32();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(MathFloorOfDiv)
 
@@ skipping 2395 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_