Report promise reject with no handler (behind a flag).

src/objects-printer.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/heap/objects-visiting.h"
 #include "src/jsregexp.h"
@@ skipping 545 matching lines @@
 void JSValue::JSValuePrint(OStream& os) {  // NOLINT
   HeapObject::PrintHeader(os, "ValueObject");
   value()->Print(os);
 }
 
 
 void JSMessageObject::JSMessageObjectPrint(OStream& os) {  // NOLINT
   HeapObject::PrintHeader(os, "JSMessageObject");
   os << " - type: " << Brief(type());
   os << "\n - arguments: " << Brief(arguments());
+  os << "\n - promise: " << Brief(promise());
   os << "\n - start_position: " << start_position();
   os << "\n - end_position: " << end_position();
   os << "\n - script: " << Brief(script());
   os << "\n - stack_frames: " << Brief(stack_frames());
   os << "\n";
 }
 
 
 void String::StringPrint(OStream& os) {  // NOLINT
   if (StringShape(this).IsInternalized()) {
@@ skipping 527 matching lines @@
     }
   }
   os << "\n";
 }
 
 
 #endif  // OBJECT_PRINT
 
 
 } }  // namespace v8::internal