Use VM tag in profile and add stack trace trie

runtime/bin/vmservice/client/lib/src/service/cache.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.
 
 part of service;
 
 /// Abstract [ServiceObjectCache].
 abstract class ServiceObjectCache<T extends ServiceObject> {
   final Isolate isolate;
   final _cache = new ObservableMap<String, T>();
@@ skipping 95 matching lines @@
     codeList.sort((Code a, Code b) {
       return b.exclusiveTicks - a.exclusiveTicks;
     });
     if (codeList.length < count) {
       return codeList;
     }
     codeList.length = count;
     return codeList;
   }
 
+  Code tagRoot() {
+    return _cache['code/tag-0'];
+  }
+
   void _resetProfileData() {
     _cache.forEach((k, Code code) {
       code.resetProfileData();
     });
   }
 
   void _updateProfileData(ServiceMap profile, List<Code> codeTable) {
     var codeRegions = profile['codes'];
     var sampleCount = profile['samples'];
     for (var codeRegion in codeRegions) {
@@ skipping 21 matching lines @@
 
   bool cachesType(String type) => ServiceObject.stripRef(type) == 'Function';
   ServiceMap _upgrade(ObservableMap obj) =>
       new ServiceMap.fromMap(isolate, obj);
 
   static final RegExp _matcher =
       new RegExp(r'^functions/native-.+|'
                  r'^functions/collected-.+|'
                  r'^functions/reused-.+|'
                  r'^functions/stub-.+|'
+                 r'^functions/tag-.+|'
                  r'^classes/\d+/functions/.+|'
                  r'^classes/\d+/closures/.+|'
                  r'^classes/\d+/implicit_closures/.+|'
                  r'^classes/\d+/dispatchers/.+');
 }