Revert r20476.

src/x64/lithium-x64.cc

 // 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 1907 matching lines @@
       }
     }
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoCheckHeapObject(HCheckHeapObject* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
-  LInstruction* result = new(zone()) LCheckNonSmi(value);
-  if (!instr->value()->IsHeapObject()) result = AssignEnvironment(result);
-  return result;
+  return AssignEnvironment(new(zone()) LCheckNonSmi(value));
 }
 
 
 LInstruction* LChunkBuilder::DoCheckSmi(HCheckSmi* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   return AssignEnvironment(new(zone()) LCheckSmi(value));
 }
 
 
 LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
@@ skipping 662 matching lines @@
   LOperand* index = UseTempRegister(instr->index());
   LLoadFieldByIndex* load = new(zone()) LLoadFieldByIndex(object, index);
   LInstruction* result = DefineSameAsFirst(load);
   return AssignPointerMap(result);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64