Make pub strong-mode clean.

lib/src/barback/pub_package_provider.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.
 
 import 'dart:async';
 import 'dart:io';
 
+import 'package:async/async.dart';
 import 'package:barback/barback.dart';
+import 'package:collection/collection.dart';
 import 'package:path/path.dart' as path;
+import 'package:pub_semver/pub_semver.dart';
 
 import '../io.dart';
+import '../package.dart';
 import '../package_graph.dart';
 import '../preprocess.dart';
 import '../sdk.dart' as sdk;
-import '../utils.dart';
 
 /// The path to the lib directory of the compiler_unsupported package used by
 /// pub.
 ///
 /// This is used to make sure dart2js is running against its own version of its
 /// internal libraries when running from the pub repo. It's `null` if we're
 /// running from the Dart repo or from the built SDK.
 final _compilerUnsupportedLib = (() {
   if (runningFromSdk) return null;
   if (runningFromDartRepo) return null;
@@ skipping 30 matching lines @@
       var file = assetPath(path.joinAll(components));
       _assertExists(file, id);
 
       // Barback may not be in the package graph if there are no user-defined
       // transformers being used at all. The "$pub" sources are still provided,
       // but will never be loaded.
       if (!_graph.packages.containsKey("barback")) {
         return new Asset.fromPath(id, file);
       }
 
-      var versions = mapMap(_graph.packages,
+      var versions = mapMap/*<String, Package, String, Version>*/(
+          _graph.packages,
           value: (_, package) => package.version);
       var contents = readTextFile(file);
       contents = preprocess(contents, versions, path.toUri(file));
       return new Asset.fromString(id, contents);
     }
 
     // "$sdk" is a pseudo-package that provides access to the Dart library
     // sources in the SDK. The dart2js transformer uses this to locate the Dart
     // sources for "dart:" libraries.
     if (id.package == r'$sdk') {
@@ skipping 11 matching lines @@
         return new Asset.fromPath(id, file);
       }
 
       // If we're running from pub's repo, our version of dart2js comes from
       // compiler_unsupported and may expect different SDK sources than the
       // actual SDK we're using. Handily, compiler_unsupported contains a full
       // (ZLib-encoded) copy of the SDK, so we load sources from that instead.
       var file = path.join(_compilerUnsupportedLib, 'sdk',
           path.joinAll(parts.skip(1))) + "_";
       _assertExists(file, id);
-      return new Asset.fromStream(id, callbackStream(() =>
+      return new Asset.fromStream(id, new LazyStream(() =>
           _zlib.decoder.bind(new File(file).openRead())));
     }
 
     var nativePath = path.fromUri(id.path);
     var file = _graph.packages[id.package].path(nativePath);
     _assertExists(file, id);
     return new Asset.fromPath(id, file);
   }
 
   /// Throw an [AssetNotFoundException] for [id] if [path] doesn't exist.
@@ skipping 41 matching lines @@
     } else {
       var package = _graph.packages[packageName];
       return new Stream.fromIterable(
           package.listFiles(beneath: 'lib').map((file) {
         return new AssetId(packageName,
             path.toUri(package.relative(file)).toString());
       }));
     }
   }
 }