add support for native methods in class

pkg/front_end/lib/src/fasta/source/stack_listener.dart

 // Copyright (c) 2016, 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 fasta.stack_listener;
 
 import 'package:kernel/ast.dart' show AsyncMarker, Expression;
 
 import '../deprecated_problems.dart' show deprecated_inputError;
 
-import '../fasta_codes.dart' show Message, templateInternalProblemStackNotEmpty;
+import '../fasta_codes.dart'
+    show
+        Message,
+        messageNativeClauseShouldBeAnnotation,
+        templateInternalProblemStackNotEmpty;
 
 import '../messages.dart' as messages;
 
 import '../parser.dart' show Listener, MemberKind;
 
 import '../parser/identifier_context.dart' show IdentifierContext;
 
 import '../problems.dart'
     show internalProblem, unhandled, unimplemented, unsupported;
 
@@ skipping 19 matching lines @@
   FormalParameters,
   FunctionBody,
   FunctionBodyAsyncToken,
   FunctionBodyStarToken,
   Identifier,
   IdentifierList,
   Initializers,
   Metadata,
   Modifiers,
   ParameterDefaultValue,
+  StringLiteral,
   SwitchScope,
   Type,
   TypeArguments,
   TypeList,
   TypeVariable,
   TypeVariables,
 }
 
 abstract class StackListener extends Listener {
   final Stack stack = new Stack();
@@ skipping 198 matching lines @@
     debugEvent("CaseExpression");
   }
 
   @override
   void endCatchClause(Token token) {
     debugEvent("CatchClause");
   }
 
   @override
   void handleRecoverableError(Token token, Message message) {
+    if (message == messageNativeClauseShouldBeAnnotation) return;
     debugEvent("Error: ${message.message}");
     addCompileTimeError(message, token.offset);
   }
 
   void addCompileTimeError(Message message, int charOffset);
 
   @override
   Token handleUnrecoverableError(Token token, Message message) {
     throw deprecated_inputError(uri, token.charOffset, message.message);
   }
@@ skipping 56 matching lines @@
     list.setRange(0, arrayLength, array);
     return list;
   }
 
   void _grow() {
     final List newTable = new List(array.length * 2);
     newTable.setRange(0, array.length, array, 0);
     array = newTable;
   }
 }