src: add rudimentary Promise support

This patch allows llnode to list Promise objects with findjsobjects,
findjsinstances and findrefs. We can investigate more fancy Promise
features in the future (such as listing handlers, Promise status, etc.).

src/llv8-constants.cc

@@ -496,6 +496,7 @@ void Types::Load() {
   kLastContextType = LoadConstant("LastContextType");
 
   kJSErrorType = LoadConstant("type_JSError__JS_ERROR_TYPE");
+  kJSPromiseType = LoadConstant("type_JSPromise__JS_PROMISE_TYPE");
   kHeapNumberType = LoadConstant("type_HeapNumber__HEAP_NUMBER_TYPE");
   kMapType = LoadConstant("type_Map__MAP_TYPE");
   kGlobalObjectType =

src/llv8-constants.h

@@ -491,6 +491,7 @@ class Types : public Module {
   int64_t kLastContextType;
 
   int64_t kJSErrorType;
+  int64_t kJSPromiseType;
   int64_t kHeapNumberType;
   int64_t kMapType;
   int64_t kGlobalObjectType;

src/llv8-inl.h

@@ -239,6 +239,7 @@ inline bool JSObject::IsObjectType(LLV8* v8, int64_t type) {
   return type == v8->types()->kJSObjectType ||
          type == v8->types()->kJSAPIObjectType ||
          type == v8->types()->kJSErrorType ||
+         type == v8->types()->kJSPromiseType ||
          type == v8->types()->kJSSpecialAPIObjectType;
 }