Add the analysis options path to the diagnostics page.

pkg/analyzer/lib/context/context_root.dart

 // Copyright (c) 2017, 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.
 
 import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:path/path.dart' as path;
 
 /**
  * Information about the root directory associated with an analysis context.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 class ContextRoot {
   /**
    * The absolute path of the root directory containing the files to be
    * analyzed.
    */
   final String root;
 
   /**
    * A list of the absolute paths of files and directories within the root
    * directory that should not be analyzed.
    */
   final List<String> exclude;
 
   /**
+   * An informative value for the file path that the analysis options were read
+   * from. This value can be `null` if there is no analysis options file or if
+   * the location of the file has not yet been discovered.
+   */
+  String optionsFilePath;
+
+  /**
    * Initialize a newly created context root.
    */
   ContextRoot(this.root, this.exclude);
 
   @override
   int get hashCode {
     int hash = 0;
     hash = JenkinsSmiHash.combine(hash, root.hashCode);
     hash = JenkinsSmiHash.combine(hash, exclude.hashCode);
     return JenkinsSmiHash.finish(hash);
@@ skipping 41 matching lines @@
       return false;
     }
     for (int i = 0; i < listA.length; i++) {
       if (!itemEqual(listA[i], listB[i])) {
         return false;
       }
     }
     return true;
   }
 }