Define DEBUG for v8_optimized_debug=2

src/checks.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 111 matching lines @@
   va_start(arguments, format);
   i::OS::VPrintError(format, arguments);
   va_end(arguments);
   i::OS::PrintError("\n#\n\n");
   i::OS::Abort();
 }
 
 
 namespace v8 { namespace internal {
 
-  bool EnableSlowAsserts() { return FLAG_enable_slow_asserts; }
-
   intptr_t HeapObjectTagMask() { return kHeapObjectTagMask; }
 
 } }  // namespace v8::internal