Fix legacy const for-of/in destructuring

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index f122d9aa5e4b57ff1459cfa48e060c666bd407ff..8a6f2ebd9c6e445070e0cde3c4abaa567e7d64e9 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -2553,7 +2553,9 @@ void Parser::ParseVariableDeclarations(VariableDeclarationContext var_context,
     is_for_iteration_variable =
         var_context == kForStatement &&
         (peek() == Token::IN || PeekContextualKeyword(CStrVector("of")));
-    if (is_for_iteration_variable && parsing_result->descriptor.mode == CONST) {
+    if (is_for_iteration_variable &&
+        (parsing_result->descriptor.mode == CONST ||
+         parsing_result->descriptor.mode == CONST_LEGACY)) {
       parsing_result->descriptor.needs_init = false;
     }