Add support for enabling DCHECKs in release mode

src/layout-descriptor.h

 // Copyright 2014 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.
 
 #ifndef V8_LAYOUT_DESCRIPTOR_H_
 #define V8_LAYOUT_DESCRIPTOR_H_
 
 #include <iosfwd>
 
 #include "src/objects.h"
@@ skipping 43 matching lines @@
   // |map|'s layout descriptor and if it is still fast then returns it.
   // Otherwise the |full_layout_descriptor| is returned.
   static Handle<LayoutDescriptor> AppendIfFastOrUseFull(
       Handle<Map> map, PropertyDetails details,
       Handle<LayoutDescriptor> full_layout_descriptor);
 
   // Layout descriptor that corresponds to an object all fields of which are
   // tagged (FastPointerLayout).
   V8_INLINE static LayoutDescriptor* FastPointerLayout();
 
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_DCHECKS
   // Check that this layout descriptor corresponds to given map.
   bool IsConsistentWithMap(Map* map);
 #endif
 
 #ifdef OBJECT_PRINT
   // For our gdb macros, we should perhaps change these in the future.
   void Print();
 
   void Print(std::ostream& os);  // NOLINT
 #endif
@@ skipping 43 matching lines @@
 
  private:
   bool all_fields_tagged_;
   int header_size_;
   LayoutDescriptor* layout_descriptor_;
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_LAYOUT_DESCRIPTOR_H_