invoke computeCache when priority sources change

pkg/analysis_server/lib/src/analysis_server.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.
 
 library analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/analysis_logger.dart';
@@ skipping 264 matching lines @@
    * Return `null` if there is no such context.
    */
   AnalysisContext getAnalysisContext(String path) {
     // try to find a containing context
     for (Folder folder in folderMap.keys) {
       if (folder.contains(path)) {
         return folderMap[folder];
       }
     }
     // check if there is a context that analyzed this source
-    Source source = getSource(path);
+    return getAnalysisContextForSource(getSource(path));
+  }
+
+  /**
+   * Return the [AnalysisContext] that is used to analyze the given [source].
+   * Return `null` if there is no such context.
+   */
+  AnalysisContext getAnalysisContextForSource(Source source) {
     for (AnalysisContext context in folderMap.values) {
       SourceKind kind = context.getKindOf(source);
       if (kind != null) {
         return context;
       }
     }
     return null;
   }
 
   /**
@@ skipping 738 matching lines @@
    * [packageUriResolver].
    */
   SourceFactory _createSourceFactory(UriResolver packageUriResolver) {
     List<UriResolver> resolvers = <UriResolver>[
         new DartUriResolver(analysisServer.defaultSdk),
         new ResourceUriResolver(resourceProvider),
         packageUriResolver];
     return new SourceFactory(resolvers);
   }
 }