Trigger debug event on not yet caught exception in promises.

src/debug.h

 // Copyright 2012 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 775 matching lines @@
   void DebugRequest(const uint16_t* json_request, int length);
 
   MUST_USE_RESULT MaybeHandle<Object> MakeJSObject(
       Vector<const char> constructor_name,
       int argc,
       Handle<Object> argv[]);
   MUST_USE_RESULT MaybeHandle<Object> MakeExecutionState();
   MUST_USE_RESULT MaybeHandle<Object> MakeBreakEvent(
       Handle<Object> break_points_hit);
   MUST_USE_RESULT MaybeHandle<Object> MakeExceptionEvent(
-      Handle<Object> exception, bool uncaught);
+      Handle<Object> exception,
+      bool uncaught,
+      Handle<Object> promise);
   MUST_USE_RESULT MaybeHandle<Object> MakeCompileEvent(
       Handle<Script> script, bool before);
   MUST_USE_RESULT MaybeHandle<Object> MakeScriptCollectedEvent(int id);
 
   void OnDebugBreak(Handle<Object> break_points_hit, bool auto_continue);
-  void OnException(Handle<Object> exception, bool uncaught);
+  void OnException(Handle<Object> exception,
+                   bool uncaught,
+                   Handle<Object> promise = Handle<Object>::null());
   void OnBeforeCompile(Handle<Script> script);
 
   enum AfterCompileFlags {
     NO_AFTER_COMPILE_FLAGS,
     SEND_WHEN_DEBUGGING
   };
   void OnAfterCompile(Handle<Script> script,
                       AfterCompileFlags after_compile_flags);
   void OnScriptCollected(int id);
   void ProcessDebugEvent(v8::DebugEvent event,
@@ skipping 245 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(MessageDispatchHelperThread);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_DEBUG_H_