Revert "Replace HeapNumber as doublebox with an explicit MutableHeapNumber."

src/x87/stub-cache-x87.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/codegen.h"
 #include "src/ic-inl.h"
@@ skipping 505 matching lines @@
         if (it.Done()) {
           __ j(not_equal, miss_label);
           break;
         }
         __ j(equal, &do_store, Label::kNear);
       }
       __ bind(&do_store);
     }
   } else if (representation.IsDouble()) {
     Label do_store, heap_number;
-    __ AllocateHeapNumber(storage_reg, scratch1, scratch2, slow, MUTABLE);
+    __ AllocateHeapNumber(storage_reg, scratch1, scratch2, slow);
 
     __ JumpIfNotSmi(value_reg, &heap_number);
     __ SmiUntag(value_reg);
     __ push(value_reg);
     __ fild_s(Operand(esp, 0));
     __ pop(value_reg);
     __ SmiTag(value_reg);
     __ jmp(&do_store);
 
     __ bind(&heap_number);
@@ skipping 953 matching lines @@
   // -----------------------------------
   TailCallBuiltin(masm, Builtins::kKeyedLoadIC_Miss);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X87