Add missing import.

dart/site/try/src/compiler_isolate.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 compiler_isolate;
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:isolate';
 import 'dart:convert' show JSON;
 
 import 'compilation.dart' show PRIVATE_SCHEME;
 
 import 'package:compiler/compiler.dart' as compiler;
 
 import 'package:dart2js_incremental/dart2js_incremental.dart' show
     reuseCompiler;
 
+import 'package:compiler/implementation/dart2jslib.dart' show
+    Compiler;
+
 const bool THROW_ON_ERROR = false;
 
 final cachedSources = new Map<Uri, Future<String>>();
 
 Uri sdkLocation;
 List options = [];
 
 var communicateViaBlobs;
 
 var cachedCompiler;
@@ skipping 134 matching lines @@
   port.send(replyTo.sendPort);
   replyTo.listen((message) {
     try {
       List list = message as List;
       compile(list[0], list[1]);
     } catch (exception, stack) {
       port.send('$exception\n$stack');
     }
   });
 }