[async-iteration] add support for for-await-of loops in Async Functions

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 72659c2b63ce3c3b4a3c841e9a6e62e23b2f931a..3aa48fb62e1d1f9321cb91a40ac7d1aa2c86df81 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -765,6 +765,11 @@ class PreParserFactory {
     return PreParserStatement::Default();
   }
 
+  PreParserStatement NewForOfStatement(ZoneList<const AstRawString*>* labels,
+                                       int pos) {
+    return PreParserStatement::Default();
+  }
+
   PreParserExpression NewCallRuntime(Runtime::FunctionId id,
                                      ZoneList<PreParserExpression>* arguments,
                                      int pos) {
@@ -1317,6 +1322,14 @@ class PreParser : public ParserBase<PreParser> {
     return stmt;
   }
 
+  V8_INLINE PreParserStatement InitializeForOfStatement(
+      PreParserStatement stmt, PreParserExpression each,
+      PreParserExpression iterable, PreParserStatement body, bool finalize,
+      IteratorType type, int next_result_pos = kNoSourcePosition) {
+    MarkExpressionAsAssigned(each);
+    return stmt;
+  }
+
   V8_INLINE PreParserStatement RewriteForVarInLegacy(const ForInfo& for_info) {
     return PreParserStatement::Null();
   }