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

src/x87/macro-assembler-x87.cc

Index: src/x87/macro-assembler-x87.cc
diff --git a/src/x87/macro-assembler-x87.cc b/src/x87/macro-assembler-x87.cc
index 111aed9a2e6b6b9cf6591f223de96348943fe643..585f9c023b4b58129a0c4eddb4cd248be3c280a6 100644
--- a/src/x87/macro-assembler-x87.cc
+++ b/src/x87/macro-assembler-x87.cc
@@ -1576,18 +1576,14 @@ void MacroAssembler::UndoAllocationInNewSpace(Register object) {
 void MacroAssembler::AllocateHeapNumber(Register result,
                                         Register scratch1,
                                         Register scratch2,
-                                        Label* gc_required,
-                                        MutableMode mode) {
+                                        Label* gc_required) {
   // Allocate heap number in new space.
   Allocate(HeapNumber::kSize, result, scratch1, scratch2, gc_required,
            TAG_OBJECT);
 
-  Handle<Map> map = mode == MUTABLE
-      ? isolate()->factory()->mutable_heap_number_map()
-      : isolate()->factory()->heap_number_map();
-
   // Set the map.
-  mov(FieldOperand(result, HeapObject::kMapOffset), Immediate(map));
+  mov(FieldOperand(result, HeapObject::kMapOffset),
+      Immediate(isolate()->factory()->heap_number_map()));
 }