implement LabeledStatement and Break in kernel

pkg/compiler/lib/src/kernel/kernel_visitor.dart

 // Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/frontend/accessors.dart'
     show
         Accessor,
         IndexAccessor,
         NullAwarePropertyAccessor,
@@ skipping 386 matching lines @@
   }
 
   ir.SwitchCase getContinueSwitchTarget(JumpTarget target) {
     return continueSwitchTargets[target];
   }
 
   ir.Statement buildBreakTarget(
       ir.Statement statement, Node node, JumpTarget jumpTarget) {
     assert(node.isValidBreakTarget());
     assert(jumpTarget == elements.getTargetDefinition(node));
+    associateNode(statement, node);
     if (jumpTarget != null && jumpTarget.isBreakTarget) {
       ir.LabeledStatement breakTarget = getBreakTarget(jumpTarget);
       breakTarget.body = statement;
       statement.parent = breakTarget;
       return breakTarget;
     } else {
       return statement;
     }
   }
 
@@ skipping 2429 matching lines @@
       : this(null, true, node, initializers);
 
   accept(ir.Visitor v) => throw "unsupported";
 
   visitChildren(ir.Visitor v) => throw "unsupported";
 
   String toString() {
     return "IrFunction($kind, $isConstructor, $node, $initializers)";
   }
 }