Add dead CodeRegionTable for tracking overwritten Dart code

runtime/bin/vmservice/client/lib/src/elements/disassembly_entry.dart

Index: runtime/bin/vmservice/client/lib/src/elements/disassembly_entry.dart
diff --git a/runtime/bin/vmservice/client/lib/src/elements/disassembly_entry.dart b/runtime/bin/vmservice/client/lib/src/elements/disassembly_entry.dart
deleted file mode 100644
index edb7b8642994c9bfd2a1055c42ffcfbecd60559e..0000000000000000000000000000000000000000
--- a/runtime/bin/vmservice/client/lib/src/elements/disassembly_entry.dart
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) 2013, 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 disassembly_entry_element;
-
-import 'package:observatory/service.dart';
-import 'package:polymer/polymer.dart';
-import 'observatory_element.dart';
-
-@CustomTag('disassembly-entry')
-class DisassemblyEntryElement extends ObservatoryElement {
-  @published CodeInstruction instruction;
-  @published Code code;
-
-  DisassemblyEntryElement.created() : super.created();
-}