Replace ResultProvider with 'aboutToComputeResult'.

pkg/analyzer/lib/src/context/context.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.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 467 matching lines @@
 
   @override
   TypeSystem get typeSystem {
     if (_typeSystem == null) {
       _typeSystem = TypeSystem.create(this);
     }
     return _typeSystem;
   }
 
   @override
+  bool aboutToComputeResult(CacheEntry entry, ResultDescriptor result) {
+    return false;
+  }
+
+  @override
   void addListener(AnalysisListener listener) {
     if (!_listeners.contains(listener)) {
       _listeners.add(listener);
     }
   }
 
   @override
   void applyAnalysisDelta(AnalysisDelta delta) {
     ChangeSet changeSet = new ChangeSet();
     delta.analysisLevels.forEach((Source source, AnalysisLevel level) {
@@ skipping 1506 matching lines @@
     }
     DartSdk sdk = factory.dartSdk;
     if (sdk == null) {
       throw new IllegalArgumentException(
           "The source factory for an SDK analysis context must have a DartUriResolver");
     }
     return new AnalysisCache(
         <CachePartition>[AnalysisEngine.instance.partitionManager.forSdk(sdk)]);
   }
 }