Fix issue with re-scoping in do expressions

R=rossberg@chromium.org
BUG=v8:4783
LOG=N

Review URL: https://codereview.chromium.org/1747853002

Cr-Commit-Position: refs/heads/master@{#34382}

src/parsing/parameter-initializer-rewriter.cc

@@ -62,7 +62,7 @@ void Rewriter::VisitClassLiteral(ClassLiteral* class_literal) {
 void Rewriter::VisitVariableProxy(VariableProxy* proxy) {
   if (proxy->is_resolved()) {
     Variable* var = proxy->var();
-    DCHECK_EQ(var->mode(), TEMPORARY);
+    if (var->mode() != TEMPORARY) return;
     if (old_scope_->RemoveTemporary(var)) {
       var->set_scope(new_scope_);
       new_scope_->AddTemporary(var);

test/mjsunit/harmony/regress/regress-4658.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-do-expressions --noharmony-iterator-close
+// Flags: --harmony-do-expressions
 
 (function testWithSimpleLoopVariable() {
   var f = (x, y = (do { var s=0; for (var e of x) s += e; s; })) => y*(y+1);