Revert "Give instances their own model class; move DartErrors out of instance-ref into their own er…

runtime/bin/vmservice/observatory/lib/src/elements/observatory_element.dart

 // 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 observatory_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:observatory/app.dart';
 import 'package:polymer/polymer.dart';
@@ skipping 93 matching lines @@
 
   String formatSize(int bytes) => Utils.formatSize(bytes);
 
   String fileAndLine(Map frame) {
     var file = frame['script'].name;
     var shortFile = file.substring(file.lastIndexOf('/') + 1);
     return "${shortFile}:${frame['line']}";
   }
 
   int parseInt(String value) => int.parse(value);
+
+  bool isNull(ref) {
+    return ref != null && ref.serviceType == 'Null';
+  }
+
+  bool isSentinel(ref) {
+    return ref != null && ref.serviceType == 'Sentinel';
+  }
+
+  bool isError(ref) {
+    return ref != null && ref.serviceType == 'Error';
+  }
+
+  bool isInt(ref) {
+    return ref != null && (ref.serviceType == 'Smi' ||
+                           ref.serviceType == 'Mint' ||
+                           ref.serviceType == 'Bigint');
+  }
+
+  bool isBool(ref) {
+    return ref != null && ref.serviceType == 'Bool';
+  }
+
+  bool isString(ref) {
+    return ref != null && ref.serviceType == 'String';
+  }
+
+  bool isInstance(ref) {
+    return ref != null && ref.serviceType == 'Instance';
+  }
+
+  bool isDouble(ref) {
+    return ref != null && ref.serviceType == 'Double';
+  }
+
+  bool isList(ref) {
+    return ref != null && (ref.serviceType == 'GrowableObjectArray' ||
+            ref.serviceType == 'Array');
+  }
+
+  bool isType(ref) {
+    return ref != null && (ref.serviceType == 'Type');
+  }
+
+  bool isUnexpected(ref) {
+    if (ref == null) return false;
+    return (!['Null',
+              'Sentinel',
+              'Smi',
+              'Mint',
+              'Bigint',
+              'Bool',
+              'String',
+              'Double',
+              'Instance',
+              'GrowableObjectArray',
+              'Array',
+              'Type',
+              'Error'].contains(ref.serviceType));
+  }
 }