Introduce a handle zapping setting, and enable it by default for release and debug

src/global-handles.cc

Index: src/global-handles.cc
diff --git a/src/global-handles.cc b/src/global-handles.cc
index c69b9e27be9209cdaf669b24d91fee2f2c308f12..274f30e1489b113ffe3b68b80673f5a29ac0c6dd 100644
--- a/src/global-handles.cc
+++ b/src/global-handles.cc
@@ -78,7 +78,7 @@ class GlobalHandles::Node {
                   Internals::kNodeIsPartiallyDependentShift);
   }
 
-#ifdef ENABLE_EXTRA_CHECKS
+#ifdef ENABLE_HANDLE_ZAPPING
   ~Node() {
     // TODO(1428): if it's a weak handle we should have invoked its callback.
     // Zap the values for eager trapping.
@@ -117,7 +117,7 @@ class GlobalHandles::Node {
   void Release() {
     ASSERT(state() != FREE);
     set_state(FREE);
-#ifdef ENABLE_EXTRA_CHECKS
+#ifdef ENABLE_HANDLE_ZAPPING
     // Zap the values for eager trapping.
     object_ = reinterpret_cast<Object*>(kGlobalHandleZapValue);
     class_id_ = v8::HeapProfiler::kPersistentHandleNoClassId;