Introduce elipses when there are long stretches of blank lines in observatory.

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;
 
 /// A [ServiceObject] is an object known to the VM service and is tied
 /// to an owning [Isolate].
 abstract class ServiceObject extends Observable {
   static int LexicalSortName(ServiceObject o1, ServiceObject o2) {
@@ skipping 1816 matching lines @@
 
 
 class ScriptLine extends Observable {
   final Script script;
   final int line;
   final String text;
   @observable int hits;
   @observable ServiceMap bpt;
   @observable bool possibleBpt = true;
 
+  bool get isBlank {
+    // Compute isBlank on demand.
+    if (_isBlank == null) {
+      _isBlank = text.trim().isEmpty;
+    }
+    return _isBlank;
+  }
+  bool _isBlank;
+
   static bool _isTrivialToken(String token) {
     if (token == 'else') {
       return true;
     }
     for (var c in token.split('')) {
       switch (c) {
         case '{':
         case '}':
         case '(':
         case ')':
@@ skipping 930 matching lines @@
     var v = list[i];
     if ((v is ObservableMap) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is ObservableList) {
       _upgradeObservableList(v, owner);
     } else if (v is ObservableMap) {
       _upgradeObservableMap(v, owner);
     }
   }
 }