Use the instance type to determine if an object is a promise.

src/runtime/runtime-debug.cc

 // 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.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/debug/debug-evaluate.h"
 #include "src/debug/debug-frames.h"
 #include "src/debug/debug-scopes.h"
@@ skipping 225 matching lines @@
     Handle<String> function =
         factory->NewStringFromAsciiChecked("[[GeneratorFunction]]");
     result->set(2, *function);
     result->set(3, generator->function());
 
     Handle<String> receiver =
         factory->NewStringFromAsciiChecked("[[GeneratorReceiver]]");
     result->set(4, *receiver);
     result->set(5, generator->receiver());
     return factory->NewJSArrayWithElements(result);
-  } else if (Object::IsPromise(object)) {
+  } else if (object->IsJSPromise()) {
     Handle<JSObject> promise = Handle<JSObject>::cast(object);
 
     Handle<Object> status_obj =
         DebugGetProperty(promise, isolate->factory()->promise_state_symbol());
     CHECK(status_obj->IsSmi());
     const char* status = "rejected";
     int status_val = Handle<Smi>::cast(status_obj)->value();
     switch (status_val) {
       case +1:
         status = "resolved";
@@ skipping 1495 matching lines @@
   return Smi::FromInt(isolate->debug()->is_active());
 }
 
 
 RUNTIME_FUNCTION(Runtime_DebugBreakInOptimizedCode) {
   UNIMPLEMENTED();
   return NULL;
 }
 }  // namespace internal
 }  // namespace v8