Make pub strong-mode clean.

lib/src/entrypoint.dart

 // Copyright (c) 2012, 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:barback/barback.dart';
 import 'package:package_config/packages_file.dart' as packages_file;
 import 'package:path/path.dart' as p;
@@ skipping 89 matching lines @@
 
   /// The package graph for the application and all of its transitive
   /// dependencies.
   ///
   /// Throws a [DataError] if the `.packages` file isn't up-to-date relative to
   /// the pubspec and the lockfile.
   PackageGraph get packageGraph {
     if (_packageGraph != null) return _packageGraph;
 
     assertUpToDate();
-    var packages = new Map.fromIterable(lockFile.packages.values,
+    var packages = new Map<String, Package>.fromIterable(
+        lockFile.packages.values,
         key: (id) => id.name,
         value: (id) => cache.load(id));
     packages[root.name] = root;
 
     _packageGraph = new PackageGraph(this, lockFile, packages);
     return _packageGraph;
   }
   PackageGraph _packageGraph;
 
   /// The path to the entrypoint's "packages" directory.
@@ skipping 166 matching lines @@
         deleteEntry(p.join(_precompiledDepsPath, package));
       }
       rethrow;
     }
   }
 
   /// Returns the set of dependencies that need to be precompiled.
   ///
   /// If [changed] is passed, only dependencies whose contents might be changed
   /// if one of the given packages changes will be returned.
-  Set<String> _dependenciesToPrecompile({Iterable<String> changed}) {
+  Set<String> _dependenciesToPrecompile({Set<String> changed}) {
     return packageGraph.packages.values.where((package) {
       if (package.pubspec.transformers.isEmpty) return false;
       if (packageGraph.isPackageMutable(package.name)) return false;
       if (!dirExists(p.join(_precompiledDepsPath, package.name))) return true;
       if (changed == null) return true;
 
       /// Only recompile [package] if any of its transitive dependencies have
       /// changed. We check all transitive dependencies because it's possible
       /// that a transformer makes decisions based on their contents.
       return overlaps(
@@ skipping 380 matching lines @@
     _linkOrDeleteSecondaryPackageDir(dir);
     _listDirWithoutPackages(dir)
         .where(dirExists)
         .forEach(_linkOrDeleteSecondaryPackageDir);
   }
 
   // TODO(nweiz): roll this into [listDir] in io.dart once issue 4775 is fixed.
   /// Recursively lists the contents of [dir], excluding hidden `.DS_Store`
   /// files and `package` files.
   List<String> _listDirWithoutPackages(dir) {
-    return flatten(listDir(dir).map((file) {
+    return listDir(dir).expand/*<String>*/((file) {
       if (p.basename(file) == 'packages') return [];
       if (!dirExists(file)) return [];
       var fileAndSubfiles = [file];
       fileAndSubfiles.addAll(_listDirWithoutPackages(file));
       return fileAndSubfiles;
-    }));
+    });
   }
 
   /// If [packageSymlinks] is true, creates a symlink to the "packages"
   /// directory in [dir].
   ///
   /// Otherwise, deletes a "packages" directories in [dir] if one exists.
   void _linkOrDeleteSecondaryPackageDir(String dir) {
     var symlink = p.join(dir, 'packages');
     if (entryExists(symlink)) deleteEntry(symlink);
     if (_packageSymlinks) createSymlink(packagesDir, symlink, relative: true);
   }
 }