Support for 'async' in the old formatter.

pkg/analyzer/lib/src/services/formatter_impl.dart

 // Copyright (c) 2013, 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 formatter_impl;
 
 import 'dart:math';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/parser.dart';
@@ skipping 489 matching lines @@
     if (!node.statements.isEmpty) {
       visitNodes(node.statements, precededBy: newlines, separatedBy: newlines);
       newlines();
     } else {
       preserveLeadingNewlines();
     }
     token(node.rightBracket, precededBy: unindent);
   }
 
   visitBlockFunctionBody(BlockFunctionBody node) {
+    token(node.keyword, followedBy: nonBreakingSpace);
     visit(node.block);
   }
 
   visitBooleanLiteral(BooleanLiteral node) {
     token(node.literal);
   }
 
   visitBreakStatement(BreakStatement node) {
     token(node.keyword);
     visitNode(node.label, precededBy: space);
@@ skipping 255 matching lines @@
     space();
     visit(node.uri);
     allowContinuedLines((){
       visitNodes(node.combinators, precededBy: space, separatedBy: space);
     });
     token(node.semicolon);
   }
 
   visitExpressionFunctionBody(ExpressionFunctionBody node) {
     int weight = lastSpaceWeight++;
+    token(node.keyword, followedBy: nonBreakingSpace);
     token(node.functionDefinition);
     levelSpace(weight);
     visit(node.expression);
     token(node.semicolon);
   }
 
   visitExpressionStatement(ExpressionStatement node) {
     visit(node.expression);
     token(node.semicolon);
   }
@@ skipping 1048 matching lines @@
   @override
   visitEnumConstantDeclaration(EnumConstantDeclaration node) {
     // TODO: implement visitEnumConstantDeclaration
   }
 
   @override
   visitEnumDeclaration(EnumDeclaration node) {
     // TODO: implement visitEnumDeclaration
   }
 }