Fix incorrect merge of r12822 into 3.12 branch.

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 4605 matching lines @@
 };
 
 
 class HStringAdd: public HBinaryOperation {
  public:
   HStringAdd(HValue* context, HValue* left, HValue* right)
       : HBinaryOperation(context, left, right) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetGVNFlag(kDependsOnMaps);
+    SetGVNFlag(kChangesNewSpacePromotion);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   virtual HType CalculateInferredType() {
     return HType::String();
   }
 
@@ skipping 63 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(StringCharFromCode)
 };
 
 
 class HStringLength: public HUnaryOperation {
  public:
   explicit HStringLength(HValue* string) : HUnaryOperation(string) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetGVNFlag(kDependsOnMaps);
-    SetGVNFlag(kChangesNewSpacePromotion);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   virtual HType CalculateInferredType() {
     STATIC_ASSERT(String::kMaxLength <= Smi::kMaxValue);
     return HType::Smi();
   }
@@ skipping 477 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(LoadFieldByIndex);
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_