Fixed zapping of contents

src/zone/zone-segment.cc

 // Copyright 2016 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/builtins/builtins.h"
-#include "src/builtins/builtins-utils.h"
+#include "src/zone/zone-segment.h"
 
 namespace v8 {
 namespace internal {
 
-void Builtins::Generate_IteratorPrototypeIterator(
-    CodeStubAssembler* assembler) {
-  assembler->Return(assembler->Parameter(0));
+void Segment::ZapContents() {
+#ifdef DEBUG
+  memset(start(), kZapDeadByte, capacity());
+#endif
 }
 
+void Segment::ZapHeader() {
+#ifdef DEBUG
+  memset(this, kZapDeadByte, sizeof(Segment));
+#endif
+}
 }  // namespace internal
 }  // namespace v8