Do not change environment between simulate and scope with no observable side-effects in HandlePrope…

src/hydrogen.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 6972 matching lines @@
     AddInstruction(instr);
     if (instr->HasObservableSideEffects()) {
       AddSimulate(expr->AssignmentId(), REMOVABLE_SIMULATE);
     }
     return ast_context()->ReturnValue(Pop());
 
   } else {
     // Keyed store.
     CHECK_ALIVE(VisitForValue(prop->key()));
     CHECK_ALIVE(VisitForValue(expr->value()));
-    HValue* value = Pop();
-    HValue* key = Pop();
-    HValue* object = Pop();
+    HValue* value = environment()->ExpressionStackAt(0);
+    HValue* key = environment()->ExpressionStackAt(1);
+    HValue* object = environment()->ExpressionStackAt(2);
     bool has_side_effects = false;
     HandleKeyedElementAccess(object, key, value, expr, expr->AssignmentId(),
                              expr->position(),
                              true,  // is_store
                              &has_side_effects);
+    Drop(3);
     Push(value);
     AddSimulate(expr->AssignmentId(), REMOVABLE_SIMULATE);
     return ast_context()->ReturnValue(Pop());
   }
 }
 
 
 // Because not every expression has a position and there is not common
 // superclass of Assignment and CountOperation, we cannot just pass the
 // owning expression instead of position and ast_id separately.
@@ skipping 4863 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal