Update charted to 0.4.8 and roll

packages/package_config/lib/src/packages_io_impl.dart

Index: packages/package_config/lib/src/packages_io_impl.dart
diff --git a/packages/package_config/lib/src/packages_io_impl.dart b/packages/package_config/lib/src/packages_io_impl.dart
index 21b61fdab0591cc483d1af2d53cee5515f659d90..0e9474639420d7552a6f0d524cfd05f71b161121 100644
--- a/packages/package_config/lib/src/packages_io_impl.dart
+++ b/packages/package_config/lib/src/packages_io_impl.dart
@@ -14,15 +14,21 @@ import "packages_impl.dart";
 /// A [Packages] implementation based on a local directory.
 class FilePackagesDirectoryPackages extends PackagesBase {
   final Directory _packageDir;
+  final Map<String, Uri> _packageToBaseUriMap = <String, Uri>{};
+
   FilePackagesDirectoryPackages(this._packageDir);
 
-  Uri getBase(String packageName) =>
-    new Uri.file(path.join(_packageDir.path, packageName, '.'));
+  Uri getBase(String packageName) {
+    return _packageToBaseUriMap.putIfAbsent(packageName, () {
+      return new Uri.file(path.join(_packageDir.path, packageName, '.'));
+    });
+  }
 
   Iterable<String> _listPackageNames() {
-    return _packageDir.listSync()
-    .where((e) => e is Directory)
-    .map((e) => path.basename(e.path));
+    return _packageDir
+        .listSync()
+        .where((e) => e is Directory)
+        .map((e) => path.basename(e.path));
   }
 
   Iterable<String> get packages => _listPackageNames();