Implement character offsets for fields and enum constants.

runtime/observatory/tests/service/get_source_report_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.
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'service_test_common.dart';
 import 'dart:developer';
@@ skipping 45 matching lines @@
   expect(stack['frames'].length, greaterThanOrEqualTo(2));
   expect(stack['frames'][0].function.name, equals('myFunction'));
   expect(stack['frames'][0].function.dartOwner.name, equals('MyClass'));
 
   var func = stack['frames'][0].function;
   expect(func.name, equals('myFunction'));
   await func.load();
 
   var expectedRange = {
     'scriptIndex': 0,
-    'startPos': ifKernel(489, 39),
+    'startPos': ifKernel(501, 39),
     'endPos': ifKernel(633, 88),
     'compiled': true,
     'coverage': {
       'hits': ifKernel([539, 590, 619], [54, 72, 82]),
       'misses': ifKernel([552], [60])
     }
   };
 
   // Full script
   var params = { 'reports' : ['Coverage'],
@@ skipping 76 matching lines @@
     expect(e.message,
            "getSourceReport: the 'endTokenPos' parameter requires the "
            "\'scriptId\' parameter");
   }
   expect(caughtException, isTrue);
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeConcurrent: testFunction);