WIP [esnext] implement async iteration proposal

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index 45ef959ed44644d38db9b75ae6a459bc676f51b9..1d18367955e4466909b8e54e554381add2915cbc 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -28,6 +28,8 @@ class ScriptData;
 class ParserTarget;
 class ParserTargetScope;
 
+enum class IteratorType { kNormal, kAsync };
+
 class FunctionEntry BASE_EMBEDDED {
  public:
   enum {
@@ -448,7 +450,7 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
   // !%_IsJSReceiver(result = iterator.next()) &&
   //     %ThrowIteratorResultNotAnObject(result)
   Expression* BuildIteratorNextResult(Expression* iterator, Variable* result,
-                                      int pos);
+                                      IteratorType type, int pos);
 
   // Initialize the components of a for-in / for-of statement.
   Statement* InitializeForEachStatement(ForEachStatement* stmt,
@@ -458,6 +460,9 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
                                       Expression* iterable, Statement* body,
                                       bool finalize,
                                       int next_result_pos = kNoSourcePosition);
+  Statement* InitializeForAwaitOfStatement(
+      ForEachStatement* for_of, Expression* each, Expression* iterable,
+      Statement* body, bool finalize, int next_result_pos = kNoSourcePosition);
   Block* RewriteForVarInLegacy(const ForInfo& for_info);
   void DesugarBindingInForEachStatement(ForInfo* for_info, Block** body_block,
                                         Expression** each_variable, bool* ok);
@@ -635,16 +640,18 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
 
   void FinalizeIteratorUse(Scope* use_scope, Variable* completion,
                            Expression* condition, Variable* iter,
-                           Block* iterator_use, Block* result);
+                           Block* iterator_use, Block* result,
+                           IteratorType type);
 
   Statement* FinalizeForOfStatement(ForOfStatement* loop, Variable* completion,
-                                    int pos);
+                                    IteratorType type, int pos);
   void BuildIteratorClose(ZoneList<Statement*>* statements, Variable* iterator,
-                          Variable* input, Variable* output);
+                          Variable* input, Variable* output, IteratorType type);
   void BuildIteratorCloseForCompletion(Scope* scope,
                                        ZoneList<Statement*>* statements,
                                        Variable* iterator,
-                                       Expression* completion);
+                                       Expression* completion,
+                                       IteratorType type);
   Statement* CheckCallable(Variable* var, Expression* error, int pos);
 
   V8_INLINE Expression* RewriteAwaitExpression(Expression* value, int pos);