Reland improvements to causal async stack traces

runtime/observatory/lib/src/service/object.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;
 
 // Some value smaller than the object ring, so requesting a large array
 // doesn't result in an expired ref because the elements lapped it in the
 // object ring.
 const int kDefaultFieldLimit = 100;
@@ skipping 4415 matching lines @@
     this.location = map['location'];
     this.code = map['code'];
     this.variables = map['vars'] ?? [];
   }
 
   M.FrameKind _fromString(String frameKind) {
     if (frameKind == null) {
       return M.FrameKind.regular;
     }
     switch (frameKind) {
-      case 'kRegular': return M.FrameKind.regular;
-      case 'kAsyncCausal': return M.FrameKind.asyncCausal;
-      case 'kAsyncSuspensionMarker': return M.FrameKind.asyncSuspensionMarker;
+      case 'Regular': return M.FrameKind.regular;
+      case 'AsyncCausal': return M.FrameKind.asyncCausal;
+      case 'AsyncSuspensionMarker': return M.FrameKind.asyncSuspensionMarker;
       default:
         throw new UnsupportedError('Unknown FrameKind: $frameKind');
     }
   }
 
   String toString() {
     if (function != null) {
       return "Frame([$kind] ${function.qualifiedName} $location)";
     } else if (location != null) {
       return "Frame([$kind] $location)";
@@ skipping 105 matching lines @@
     var v = list[i];
     if ((v is Map) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is List) {
       _upgradeList(v, owner);
     } else if (v is Map) {
       _upgradeMap(v, owner);
     }
   }
 }