Parse ParenthesizedExpression as Fasta.

pkg/front_end/lib/src/fasta/analyzer/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' as analyzer show Token;
@@ skipping 50 matching lines @@
   createJumpTarget(JumpTargetKind kind, int charOffset) {
     // TODO(ahe): Implement jump targets.
     return null;
   }
 
   void beginLiteralString(Token token) {
     debugEvent("beginLiteralString");
     push(token);
   }
 
+  @override
+  void handleParenthesizedExpression(BeginGroupToken token) {
+    debugEvent("ParenthesizedExpression");
+    Expression expression = pop();
+    push(ast.parenthesizedExpression(
+        toAnalyzerToken(token), expression, toAnalyzerToken(token.endGroup)));
+  }
+
   void handleStringPart(Token token) {
     debugEvent("StringPart");
     push(token);
   }
 
   void doStringPart(Token token) {
     push(ast.simpleStringLiteral(toAnalyzerToken(token), token.value));
   }
 
   void endLiteralString(int interpolationCount) {
@@ skipping 1270 matching lines @@
 
 /// Data structure placed on the stack as a container for optional parameters.
 class _OptionalFormalParameters {
   final List<FormalParameter> parameters;
   final Token leftDelimiter;
   final Token rightDelimiter;
 
   _OptionalFormalParameters(
       this.parameters, this.leftDelimiter, this.rightDelimiter);
 }