Re-implement the status page for the new task model

pkg/analyzer/lib/src/context/cache.dart

 // Copyright (c) 2015, 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 analyzer.src.context.cache;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/engine.dart'
@@ skipping 295 matching lines @@
 
   /**
    * Set whether the source was explicitly added to the context to match the
    * [explicitlyAdded] flag.
    */
   void set explicitlyAdded(bool explicitlyAdded) {
     _setFlag(_EXPLICITLY_ADDED_FLAG, explicitlyAdded);
   }
 
   /**
+   * Return a list of result descriptors for results whose state is not
+   * [CacheState.INVALID].
+   */
+  List<ResultDescriptor> get nonInvalidResults => _resultMap.keys.toList();
+
+  /**
    * Fix the state of the [exception] to match the current state of the entry.
    */
   void fixExceptionState() {
     if (!hasErrorState()) {
       _exception = null;
     }
   }
 
   /**
    * Look up the [ResultData] of [descriptor], or add a new one if it isn't
@@ skipping 825 matching lines @@
   void resultAccessed(TargetedResult result) {}
 
   @override
   List<TargetedResult> resultStored(TargetedResult newResult, newValue) {
     return TargetedResult.EMPTY_LIST;
   }
 
   @override
   void targetRemoved(AnalysisTarget target) {}
 }