Issue 28466. Include ErrorProcessor(s) into the AnalysisOptions signature.

pkg/analyzer/lib/src/generated/engine.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 analyzer.src.generated.engine;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:typed_data';
 
@@ skipping 1638 matching lines @@
     if (_signature == null) {
       ApiSignature buffer = new ApiSignature();
 
       // Append boolean flags.
       buffer.addBool(enableLazyAssignmentOperators);
       buffer.addBool(enableStrictCallChecks);
       buffer.addBool(enableSuperMixins);
       buffer.addBool(strongMode);
       buffer.addBool(strongModeHints);
 
+      // Append error processors.
+      buffer.addInt(errorProcessors.length);
+      for (ErrorProcessor processor in errorProcessors) {
+        buffer.addString(processor.description);
+      }
+
       // Append lints.
       buffer.addInt(lintRules.length);
       for (Linter lintRule in lintRules) {
         buffer.addString(lintRule.lintCode.uniqueName);
       }
 
       // Hash and convert to Uint32List.
       List<int> bytes = buffer.toByteList();
       _signature = new Uint8List.fromList(bytes).buffer.asUint32List();
     }
@@ skipping 1212 matching lines @@
    */
   bool get wereSourcesAdded => _changeSet.addedSources.length > 0;
 
   /**
    * Return `true` if any sources were removed or deleted.
    */
   bool get wereSourcesRemoved =>
       _changeSet.removedSources.length > 0 ||
       _changeSet.removedContainers.length > 0;
 }