Fix source information positions for deserialized patched elements.

tests/compiler/dart2js/serialization_compilation_test.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 dart2js.serialization_compilation_test;
 
 import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/commandline_options.dart';
@@ skipping 31 matching lines @@
   String testDescription =
       test != null ? test.sourceFiles[entryPoint.path] : '${entryPoint}';
   print('------------------------------------------------------------------');
   print('compile ${testDescription}');
   print('------------------------------------------------------------------');
   OutputCollector outputCollector = new OutputCollector();
   await runCompiler(
       entryPoint: entryPoint,
       memorySourceFiles: test != null ? test.sourceFiles : const {},
       options: [Flags.disableTypeInference,
-                Flags.disableInlining,
-                // TODO(johnniwinther): Reenable this: We have some invalid
-                // locations
-                Flags.noSourceMaps],
+                Flags.disableInlining],
       outputProvider: outputCollector,
       beforeRun: (Compiler compiler) {
         deserialize(compiler, serializedData, deserializeResolvedAst: true);
       });
   if (verbose) {
     print(outputCollector.getOutput('', 'js'));
   }
 }