Get rid of ContextManager._contexts.

pkg/analysis_server/lib/src/analysis_server.dart

Index: pkg/analysis_server/lib/src/analysis_server.dart
diff --git a/pkg/analysis_server/lib/src/analysis_server.dart b/pkg/analysis_server/lib/src/analysis_server.dart
index 67e2ca9a32f3f008e9f4286b1d81e92ed3adf681..5a3cd535e99be72ae2de8b0261bbed7e65ad049b 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -1240,8 +1240,8 @@ class AnalysisServer {
   }
 
   /**
-   * Return a set of contexts containing all of the resources in the given list
-   * of [resources].
+   * Return a set of all contexts whose associated folder is contained within,
+   * or equal to, one of the resources in the given list of [resources].
    */
   Set<AnalysisContext> _getContexts(List<Resource> resources) {
     Set<AnalysisContext> contexts = new HashSet<AnalysisContext>();