For-of calls [Symbol.iterator]() on RHS to get iterator

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index 0882b250ffde424f2f86925d1416c4fa54288f54..f79c2d2b2b0ce1391b64cd4806d4d42e321ba112 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -956,11 +956,13 @@ class ForOfStatement V8_FINAL : public ForEachStatement {
   void Initialize(Expression* each,
                   Expression* subject,
                   Statement* body,
+                  Expression* assign_iterable,
                   Expression* assign_iterator,
                   Expression* next_result,
                   Expression* result_done,
                   Expression* assign_each) {
     ForEachStatement::Initialize(each, subject, body);
+    assign_iterable_ = assign_iterable;
     assign_iterator_ = assign_iterator;
     next_result_ = next_result;
     result_done_ = result_done;
@@ -971,7 +973,12 @@ class ForOfStatement V8_FINAL : public ForEachStatement {
     return subject();
   }
 
-  // var iterator = iterable;
+  // var iterable = subject;
+  Expression* assign_iterable() const {
+    return assign_iterable_;
+  }
+
+  // var iterator = iterable[Symbol.iterator]();
   Expression* assign_iterator() const {
     return assign_iterator_;
   }
@@ -1006,6 +1013,7 @@ class ForOfStatement V8_FINAL : public ForEachStatement {
         back_edge_id_(GetNextId(zone)) {
   }
 
+  Expression* assign_iterable_;
   Expression* assign_iterator_;
   Expression* next_result_;
   Expression* result_done_;