Remove signature classes from the VM.

runtime/observatory/tests/service/graph_test.dart

 // Copyright (c) 2014, 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/object_graph.dart';
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
@@ skipping 53 matching lines @@
       (ObjectVertex obj) => obj.successors.length == 2).first;
 
   // TODO(koda): Check actual byte sizes.
 
   expect(aVertex.retainedSize, equals(aVertex.shallowSize));
   expect(bVertex.retainedSize, equals(bVertex.shallowSize));
   expect(rVertex.retainedSize, equals(aVertex.shallowSize +
                                       bVertex.shallowSize +
                                       rVertex.shallowSize));
 
-  const int fixedSizeListCid = 62;
+  Library corelib =
+      isolate.libraries.singleWhere((lib) => lib.uri == 'dart:core');
+  await corelib.load();
+  Class _List =
+      corelib.classes.singleWhere((cls) => cls.vmName.startsWith('_List'));
+  int kArrayCid = _List.vmCid;
+  // startsWith to ignore the private mangling
   List<ObjectVertex> lists = new List.from(graph.vertices.where(
-      (ObjectVertex obj) => obj.vmCid == fixedSizeListCid));
+      (ObjectVertex obj) => obj.vmCid == kArrayCid));
   expect(lists.length >= 2, isTrue);
   // Order by decreasing retained size.
   lists.sort((u, v) => v.retainedSize - u.retainedSize);
   ObjectVertex first = lists[0];
   ObjectVertex second = lists[1];
   // Check that the short list retains more than the long list inside.
   expect(first.successors.length,
          equals(2 + second.successors.length));
   // ... and specifically, that it retains exactly itself + the long one.
   expect(first.retainedSize,
          equals(first.shallowSize + second.shallowSize));
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeBefore: script);