[interpreter] Use VisitForTest for loop conditions

src/interpreter/bytecode-label.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-label.h"
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
 BytecodeLabel* BytecodeLabels::New() {
+  DCHECK(!is_bound());
   labels_.push_back(BytecodeLabel());
   return &labels_.back();
 }
 
 void BytecodeLabels::Bind(BytecodeArrayBuilder* builder) {
-  for (auto label : labels_) {
+  for (auto& label : labels_) {
     builder->Bind(&label);
   }
 }
 
+void BytecodeLabels::BindToLabel(BytecodeArrayBuilder* builder,
+                                 const BytecodeLabel& target) {
+  for (auto& label : labels_) {
+    builder->Bind(target, &label);
+  }
+}
+
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8