Bug fixes and clean-up

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:collection';
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisEngine, CacheState, InternalAnalysisContext, RetentionPriority;
 import 'package:analyzer/src/generated/html.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
+import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_collection.dart';
 import 'package:analyzer/task/model.dart';
 
 /**
  * An LRU cache of results produced by analysis.
  */
 class AnalysisCache {
   /**
    * A flag used to control whether trace information should be produced when
    * the content of the cache is modified.
@@ skipping 758 matching lines @@
 class SdkCachePartition extends CachePartition {
   /**
    * Initialize a newly created cache partition, belonging to the given
    * [context]. The partition will maintain at most [maxCacheSize] AST
    * structures in the cache.
    */
   SdkCachePartition(InternalAnalysisContext context, int maxCacheSize)
       : super(context, maxCacheSize, DefaultRetentionPolicy.POLICY);
 
   @override
-  bool contains(AnalysisTarget target) => target.source.isInSystemLibrary;
+  bool contains(AnalysisTarget target) {
+    Source source = target.source;
+    return source != null && source.isInSystemLibrary;
+  }
 }
 
 /**
  * A cache partition that contains all targets not contained in other partitions.
  */
 class UniversalCachePartition extends CachePartition {
   /**
    * Initialize a newly created cache partition, belonging to the given
    * [context]. The partition will maintain at most [maxCacheSize] AST
    * structures in the cache, using the [retentionPolicy] to determine which
    * AST structures to flush.
    */
   UniversalCachePartition(InternalAnalysisContext context, int maxCacheSize,
       CacheRetentionPolicy retentionPolicy)
       : super(context, maxCacheSize, retentionPolicy);
 
   @override
   bool contains(AnalysisTarget target) => true;
 }