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

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 5f9bd78ff00eb0b888d0dc682a244ab721f4afb7..07bc737c14cb667a8f9254119e8e22915b22ae65 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -1683,18 +1683,14 @@ 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()));
 }