[kernel] Position on switch expression

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 951 matching lines @@
     writeOffset(node.bodyOffset);
     writeVariableDeclaration(node.variable);
     writeNode(node.iterable);
     writeNode(node.body);
     _variableIndexer.popScope();
   }
 
   visitSwitchStatement(SwitchStatement node) {
     _switchCaseIndexer.enter(node);
     writeByte(Tag.SwitchStatement);
+    writeOffset(node.fileOffset);
     writeNode(node.expression);
     writeNodeList(node.cases);
     _switchCaseIndexer.exit(node);
   }
 
   visitSwitchCase(SwitchCase node) {
     // Note: there is no tag on SwitchCase.
     int length = node.expressions.length;
     writeUInt30(length);
     for (int i = 0; i < length; ++i) {
@@ skipping 569 matching lines @@
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     flushedLength += length;
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }