new handleInvalidTopLevelDeclaration event in fasta parser

pkg/analyzer/lib/src/fasta/ast_builder.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.analyzer.ast_builder;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast_factory.dart' show AstFactory;
 import 'package:analyzer/dart/ast/standard_ast_factory.dart' as standard;
 import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
@@ skipping 1106 matching lines @@
         name,
         ast.functionExpression(typeParameters, parameters, body)));
   }
 
   @override
   void endTopLevelDeclaration(Token token) {
     debugEvent("TopLevelDeclaration");
   }
 
   @override
+  void handleInvalidTopLevelDeclaration(Token beginToken, Token endToken) {
+    // TODO(danrubel): consider creating a AST node
+    // representing the invalid declaration
+    // to support code completion, quick fixes, etc.
+    super.handleInvalidTopLevelDeclaration(beginToken, endToken);
+    pop(); // comment
+  }
+
+  @override
   void beginCompilationUnit(Token token) {
     push(token);
   }
 
   @override
   void endCompilationUnit(int count, Token endToken) {
     debugEvent("CompilationUnit");
     List<Object> elements = popList(count);
     Token beginToken = pop();
 
@@ skipping 865 matching lines @@
       } else if (identical('var', s)) {
         finalConstOrVarKeyword = token;
       } else if (identical('covariant', s)) {
         covariantKeyword = token;
       } else {
         unhandled("$s", "modifier", token.charOffset, null);
       }
     }
   }
 }