Do not waste space for the fast-case elements backing storage for ...

src/x64/full-codegen-x64.cc

 // Copyright 2010 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 885 matching lines @@
   Apply(context_, rax);
 }
 
 
 void FullCodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
   Comment cmnt(masm_, "[ ObjectLiteral");
   __ movq(rdi, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
   __ push(FieldOperand(rdi, JSFunction::kLiteralsOffset));
   __ Push(Smi::FromInt(expr->literal_index()));
   __ Push(expr->constant_properties());
+  __ Push(Smi::FromInt(expr->fast_elements() ? 1 : 0));
   if (expr->depth() > 1) {
-    __ CallRuntime(Runtime::kCreateObjectLiteral, 3);
+    __ CallRuntime(Runtime::kCreateObjectLiteral, 4);
   } else {
-    __ CallRuntime(Runtime::kCreateObjectLiteralShallow, 3);
+    __ CallRuntime(Runtime::kCreateObjectLiteralShallow, 4);
   }
 
   // If result_saved is true the result is on top of the stack.  If
   // result_saved is false the result is in rax.
   bool result_saved = false;
 
   for (int i = 0; i < expr->properties()->length(); i++) {
     ObjectLiteral::Property* property = expr->properties()->at(i);
     if (property->IsCompileTimeValue()) continue;
 
@@ skipping 1064 matching lines @@
   __ movq(Operand(rsp, 0), rdx);
   // And return.
   __ ret(0);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal