Make servePackages's contents argument saner.

sdk/lib/_internal/pub/test/get/hosted/get_transitive_test.dart

Index: sdk/lib/_internal/pub/test/get/hosted/get_transitive_test.dart
diff --git a/sdk/lib/_internal/pub/test/get/hosted/get_transitive_test.dart b/sdk/lib/_internal/pub/test/get/hosted/get_transitive_test.dart
index 60a9b1e98da01281bc1d3f8f78246f217b0c16b8..8c8457d34c7bc3e50ac9ee455a0a25eb6145209d 100644
--- a/sdk/lib/_internal/pub/test/get/hosted/get_transitive_test.dart
+++ b/sdk/lib/_internal/pub/test/get/hosted/get_transitive_test.dart
@@ -10,12 +10,14 @@ import '../../test_pub.dart';
 main() {
   initConfig();
   integration('gets packages transitively from a pub server', () {
-    servePackages([
-      packageMap("foo", "1.2.3", {"bar": "2.0.4"}),
-      packageMap("bar", "2.0.3"),
-      packageMap("bar", "2.0.4"),
-      packageMap("bar", "2.0.5")
-    ]);
+    servePackages((builder) {
+      builder.serve("foo", "1.2.3", pubspec: {
+        "dependencies": {"bar": "2.0.4"}
+      });
+      builder.serve("bar", "2.0.3");
+      builder.serve("bar", "2.0.4");
+      builder.serve("bar", "2.0.5");
+    });
 
     d.appDir({"foo": "1.2.3"}).create();