[kernel] Add offset to SwitchContinueStatement; add debugging test

pkg/kernel/lib/binary/ast_to_binary.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 file.
 library kernel.ast_to_binary;
 
 import '../ast.dart';
 import '../import_table.dart';
 import 'tag.dart';
 import 'dart:convert';
 import 'dart:typed_data';
@@ skipping 971 matching lines @@
     for (int i = 0; i < length; ++i) {
       writeOffset(node.expressionOffsets[i]);
       writeNode(node.expressions[i]);
     }
     writeByte(node.isDefault ? 1 : 0);
     writeNode(node.body);
   }
 
   visitContinueSwitchStatement(ContinueSwitchStatement node) {
     writeByte(Tag.ContinueSwitchStatement);
+    writeOffset(node.fileOffset);
     writeUInt30(_switchCaseIndexer[node.target]);
   }
 
   visitIfStatement(IfStatement node) {
     writeByte(Tag.IfStatement);
     writeNode(node.condition);
     writeNode(node.then);
     writeStatementOrEmpty(node.otherwise);
   }
 
@@ skipping 550 matching lines @@
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     flushedLength += length;
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }