WIP [esnext] implement async iteration proposal

src/ast/prettyprinter.cc

Index: src/ast/prettyprinter.cc
diff --git a/src/ast/prettyprinter.cc b/src/ast/prettyprinter.cc
index 463ae26c4d77eeec9d440089224cba7a0f86fb6d..c288ee7e8ca50f2e923a47fa72949e8c62f384c8 100644
--- a/src/ast/prettyprinter.cc
+++ b/src/ast/prettyprinter.cc
@@ -1199,7 +1199,9 @@ void AstPrinter::VisitEmptyParentheses(EmptyParentheses* node) {
 }
 
 void AstPrinter::VisitGetIterator(GetIterator* node) {
-  IndentedScope indent(this, "GET-ITERATOR", node->position());
+  const char* desc = node->hint() == GetIterator::kAsync ? "GET-ASYNC-ITERATOR"
+                                                         : "GET-ITERATOR";
+  IndentedScope indent(this, desc, node->position());
   Visit(node->iterable());
 }