Upgrade to analyzer 0.27.0.

lib/src/dart_formatter.dart

 // Copyright (c) 2014, 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 dart_style.src.dart_formatter;
 
 import 'dart:math' as math;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/parser.dart';
@@ skipping 83 matching lines @@
       } else {
         lineEnding = "\n";
       }
     }
 
     errorListener.throwIfErrors();
 
     // Parse it.
     var parser = new Parser(stringSource, errorListener);
 
+    parser.parseConditionalDirectives = true;
+
     var node;
     if (source.isCompilationUnit) {
       node = parser.parseCompilationUnit(startToken);
     } else {
       node = parser.parseStatement(startToken);
 
       // Make sure we consumed all of the source.
       var token = node.endToken.next;
       if (token.type != TokenType.EOF) {
         var error = new AnalysisError(
             stringSource,
             token.offset,
             math.max(token.length, 1),
             ParserErrorCode.UNEXPECTED_TOKEN,
             [token.lexeme]);
 
         throw new FormatterException([error]);
       }
     }
 
     errorListener.throwIfErrors();
 
     // Format it.
     var visitor = new SourceVisitor(this, lineInfo, source);
     return visitor.run(node);
   }
 }