[api] add API for Promise status and result.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index ed61bcc5ccd039f3d9850aa6477105d3229a5915..6a73f7c82db5e49abc93227990d5ebc66774e85a 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -16484,11 +16484,11 @@ class StringSharedKey : public HashTableKey {
 // static
 const char* JSPromise::Status(int status) {
   switch (status) {
-    case kPromiseFulfilled:
+    case v8::Promise::kFulfilled:
       return "resolved";
-    case kPromisePending:
+    case v8::Promise::kPending:
       return "pending";
-    case kPromiseRejected:
+    case v8::Promise::kRejected:
       return "rejected";
   }
   UNREACHABLE();