Restore invariant that stack is empty in parseFunctionBody.

pkg/analyzer/test/generated/parser_fasta_test.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/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart' as analyzer;
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/fasta/ast_builder.dart';
 import 'package:analyzer/src/fasta/element_store.dart';
@@ skipping 765 matching lines @@
   /**
    * Creates a [ParserProxy] which is prepared to begin parsing at the given
    * Fasta token.
    */
   factory ParserProxy(analyzer.Token startingToken,
       {bool enableGenericMethodComments: false}) {
     var library = new KernelLibraryBuilderProxy();
     var member = new BuilderProxy();
     var elementStore = new ElementStoreProxy();
     var scope = new ScopeProxy();
-    var astBuilder = new AstBuilder(null, library, member, elementStore, scope);
+    var astBuilder =
+        new AstBuilder(null, library, member, elementStore, scope, true);
     astBuilder.parseGenericMethodComments = enableGenericMethodComments;
     var fastaParser = new fasta.Parser(astBuilder);
     astBuilder.parser = fastaParser;
     return new ParserProxy._(startingToken, fastaParser, astBuilder);
   }
 
   ParserProxy._(this._currentFastaToken, this._fastaParser, this._astBuilder);
 
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
@@ skipping 156 matching lines @@
   }
 
   @override
   @failingTest
   void test_parsePartOfDirective_uri() {
     // TODO(paulberry,ahe): URIs in "part of" declarations are not supported by
     // Fasta.
     super.test_parsePartOfDirective_uri();
   }
 }