src: add rudimentary Promise support

src/llv8-constants.cc

@@ -518,6 +518,13 @@ void Types::Load() {
   kLastContextType = LoadConstant("LastContextType");
 
   kJSErrorType = LoadConstant("type_JSError__JS_ERROR_TYPE");
+  kJSPromiseType = LoadConstant("type_JSPromise__JS_PROMISE_TYPE");
+  if (kJSPromiseType == -1) {
+    // NOTE(mmarchini): On Node.js v10.x, JS_PROMISE always comes after
+    // JS_MESSAGE_OBJECT_TYPE in the InstanceType enum.
+    kJSPromiseType =
+        LoadConstant("type_JSMessageObject__JS_MESSAGE_OBJECT_TYPE") + 1;
+  }
   kHeapNumberType = LoadConstant("type_HeapNumber__HEAP_NUMBER_TYPE");
   kMapType = LoadConstant("type_Map__MAP_TYPE");
   kGlobalObjectType =

src/llv8-constants.h

@@ -507,6 +507,7 @@ 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

@@ -314,6 +314,7 @@ 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;
 }
 

test/fixtures/inspect-scenario.js

@@ -67,6 +67,8 @@ function closure() {
   c.hashmap['stringifiedError'] = new Error('test');
   c.hashmap['stringifiedErrorStack'] = c.hashmap['stringifiedError'].stack;
 
+  c.hashmap['promise'] = new Promise(() => {});
+
   c.hashmap[0] = null;
   c.hashmap[4] = undefined;
   c.hashmap[23] = /regexp/;

test/plugin/inspect-test.js

@@ -187,6 +187,10 @@ const hashMapTests = {
       });
     }
   },
+  'promise': {
+    re: /.promise=(0x[0-9a-f]+):<Object: Promise>/,
+    desc: '.promise Promise property'
+  },
   // .array=0x000003df9cbe7919:<Array: length=6>,
   'array': {
     re: /.array=(0x[0-9a-f]+):<Array: length=6>/,