Trigger exception debug event for promises at the throw site.

include/v8-debug.h

Index: include/v8-debug.h
diff --git a/include/v8-debug.h b/include/v8-debug.h
index 8523387a51a487bf9d0937dd1a671e83e2889806..bd3eb77c4d72aca11d7f58b8d3e9720a474fe739 100644
--- a/include/v8-debug.h
+++ b/include/v8-debug.h
@@ -20,8 +20,7 @@ enum DebugEvent {
   BeforeCompile = 4,
   AfterCompile  = 5,
   ScriptCollected = 6,
-  PendingExceptionInPromise = 7,
-  BreakForCommand = 8
+  BreakForCommand = 7
 };