Remove unused byte from Map::instance_sizes field.

src/arm64/macro-assembler-arm64.h

Index: src/arm64/macro-assembler-arm64.h
diff --git a/src/arm64/macro-assembler-arm64.h b/src/arm64/macro-assembler-arm64.h
index 7854ff0e520987e4683847ba921d2d77a7e16188..8d47272526ce0992e8b0e2020b326900ca5994ac 100644
--- a/src/arm64/macro-assembler-arm64.h
+++ b/src/arm64/macro-assembler-arm64.h
@@ -1305,12 +1305,6 @@ class MacroAssembler : public Assembler {
                 Label* gc_required,
                 AllocationFlags flags);
 
-  // Undo allocation in new space. The object passed and objects allocated after
-  // it will no longer be allocated. The caller must make sure that no pointers
-  // are left to the object(s) no longer allocated as they would be invalid when
-  // allocation is undone.
-  void UndoAllocationInNewSpace(Register object, Register scratch);
-
   void AllocateTwoByteString(Register result,
                              Register length,
                              Register scratch1,