WIP [esnext] implement async iteration proposal

src/objects-printer.cc

Index: src/objects-printer.cc
diff --git a/src/objects-printer.cc b/src/objects-printer.cc
index 9e7cc25d0b9b592dc36a827c38269599e18ecaae..aaa9c61b82e6ce8ecc9098348a2e28e9b1f5f7c2 100644
--- a/src/objects-printer.cc
+++ b/src/objects-printer.cc
@@ -150,6 +150,7 @@ void HeapObject::HeapObjectPrint(std::ostream& os) {  // NOLINT
     case JS_SPECIAL_API_OBJECT_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
+    case JS_ASYNC_GENERATOR_OBJECT_TYPE:
     case JS_ARGUMENTS_TYPE:
     case JS_ERROR_TYPE:
     case JS_PROMISE_CAPABILITY_TYPE:
@@ -1264,6 +1265,26 @@ void PromiseReactionJobInfo::PromiseReactionJobInfoPrint(
   os << "\n";
 }
 
+void AsyncGeneratorRequest::AsyncGeneratorRequestPrint(
+    std::ostream& os) {  // NOLINT
+  HeapObject::PrintHeader(os, "AsyncGeneratorRequest");
+  const char* mode = "Invalid!";
+  switch (resume_mode()) {
+    case JSGeneratorObject::kNext:
+      mode = ".next()";
+      break;
+    case JSGeneratorObject::kReturn:
+      mode = ".return()";
+      break;
+    case JSGeneratorObject::kThrow:
+      mode = ".throw()";
+      break;
+  }
+  os << "\n - resume mode: " << mode;
+  os << "\n - value: " << Brief(value());
+  os << "\n";
+}
+
 void ModuleInfoEntry::ModuleInfoEntryPrint(std::ostream& os) {  // NOLINT
   HeapObject::PrintHeader(os, "ModuleInfoEntry");
   os << "\n - export_name: " << Brief(export_name());