fix #26122, classify strong mode errors correctly

pkg/analyzer/lib/source/error_processor.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.source.error_processor;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/src/task/options.dart';
@@ skipping 103 matching lines @@
 
   // TODO(rnystrom): As far as I know, this is only used to implement
   // appliesTo(). Consider making it private in ErrorProcessor if possible.
   String get code => throw new UnsupportedError(
       "_StrongModeTypeErrorProcessor is not specific to an error code.");
 
   /// In strong mode, type warnings are upgraded to errors.
   ErrorSeverity get severity => ErrorSeverity.ERROR;
 
   /// Check if this processor applies to the given [error].
-  bool appliesTo(AnalysisError error) =>
-      error.errorCode.type == ErrorType.STATIC_TYPE_WARNING;
+  bool appliesTo(AnalysisError error) {
+    ErrorCode errorCode = error.errorCode;
+    if (errorCode is StaticTypeWarningCode) {
+      return true;
+    }
+    if (errorCode is StaticWarningCode) {
+      return errorCode.isStrongModeError;
+    }
+    return false;
+  }
 }