Drop support for older Barback versions.

lib/src/asset/dart/serialize.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 pub.asset.serialize;
 
 import 'dart:async';
 import 'dart:isolate';
 
 import 'package:barback/barback.dart';
 
-//# if source_maps >=0.9.0 <0.10.0
-//> import 'package:source_maps/span.dart';
-//# end
-
 //# if source_span
 import 'package:source_span/source_span.dart';
 //# end
 
 import 'serialize/exception.dart';
 import 'utils.dart';
 
 export 'serialize/aggregate_transform.dart';
 export 'serialize/exception.dart';
 export 'serialize/transform.dart';
@@ skipping 24 matching lines @@
   return new SourceSpan(
       deserializeLocation(span['start']),
       deserializeLocation(span['end']),
       span['text']);
 }
 
 /// Converts [location] into a serializable map.
 ///
 /// [location] may be a [SourceLocation] or a [SourceLocation].
 Map serializeLocation(location) {
-//# if source_maps >=0.9.0 <0.10.0
-//>  if (location is Location) {
-//>    return {
-//>      'sourceUrl': location.sourceUrl,
-//>      'offset': location.offset,
-//>      'line': location.line,
-//>      'column': location.column
-//>    };
-//>  }
-//# end
-
 //# if source_span
   // TODO(nweiz): convert FileLocations to FileLocations.
   if (location is SourceLocation) {
     return {
       'sourceUrl': location.sourceUrl.toString(),
       'offset': location.offset,
       'line': location.line,
       'column': location.column
     };
   }
@@ skipping 94 matching lines @@
   var replyTo = wrappedMessage['replyTo'];
   new Future.sync(() => callback(wrappedMessage['message']))
       .then((result) => replyTo.send({'type': 'success', 'value': result}))
       .catchError((error, stackTrace) {
     replyTo.send({
       'type': 'error',
       'error': serializeException(error, stackTrace)
     });
   });
 }