[api] add API for Promise status and result.

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 16466 matching lines @@
  private:
   Handle<String> source_;
   Handle<SharedFunctionInfo> shared_;
   LanguageMode language_mode_;
   int scope_position_;
 };
 
 // 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();
   return NULL;
 }
 
 namespace {
 
 JSRegExp::Flags RegExpFlagsFromString(Handle<String> flags, bool* success) {
   JSRegExp::Flags value = JSRegExp::kNone;
@@ skipping 3938 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8