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

src/api.h

Index: src/api.h
diff --git a/src/api.h b/src/api.h
index 0f33bc815fe7bec76663be4ae7e2fb48dc558e50..85b280728bcbee2681e25b32dcdae89f2a7a2dbc 100644
--- a/src/api.h
+++ b/src/api.h
@@ -665,17 +665,22 @@ void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 #ifdef DEBUG
     // SealHandleScope may make the prev_limit to point inside the block.
     if (block_start <= prev_limit && prev_limit <= block_limit) {
-#ifdef ENABLE_EXTRA_CHECKS
+#ifdef ENABLE_HANDLE_ZAPPING
       internal::HandleScope::ZapRange(prev_limit, block_limit);
 #endif
       break;
     }
 #else
-    if (prev_limit == block_limit) break;
+    if (prev_limit == block_limit) {
+#ifdef ENABLE_HANDLE_ZAPPING
+      internal::HandleScope::ZapRange(prev_limit, block_limit);
+#endif
+      break;
+    }
 #endif
 
     blocks_.RemoveLast();
-#ifdef ENABLE_EXTRA_CHECKS
+#ifdef ENABLE_HANDLE_ZAPPING
     internal::HandleScope::ZapRange(block_start, block_limit);
 #endif
     if (spare_ != NULL) {