Make servePackages's contents argument saner.

sdk/lib/_internal/pub/test/hosted/remove_removed_transitive_dependency_test.dart

Index: sdk/lib/_internal/pub/test/hosted/remove_removed_transitive_dependency_test.dart
diff --git a/sdk/lib/_internal/pub/test/hosted/remove_removed_transitive_dependency_test.dart b/sdk/lib/_internal/pub/test/hosted/remove_removed_transitive_dependency_test.dart
index e975b05556e4ed04885ab840cc86c3677ab53d93..bf51e1192ca5c9453c8561e55b6405eaee0a3d8b 100644
--- a/sdk/lib/_internal/pub/test/hosted/remove_removed_transitive_dependency_test.dart
+++ b/sdk/lib/_internal/pub/test/hosted/remove_removed_transitive_dependency_test.dart
@@ -13,17 +13,21 @@ main() {
   forBothPubGetAndUpgrade((command) {
     integration("removes a transitive dependency that's no longer depended "
         "on", () {
-      servePackages([
-        packageMap("foo", "1.0.0", {
-          "shared-dep": "any"
-        }),
-        packageMap("bar", "1.0.0", {
-          "shared-dep": "any",
-          "bar-dep": "any"
-        }),
-        packageMap("shared-dep", "1.0.0"),
-        packageMap("bar-dep", "1.0.0")
-      ]);
+      servePackages((builder) {
+        builder.serve("foo", "1.0.0", pubspec: {
+          "dependencies": {
+            "shared-dep": "any"
+          }
+        });
+        builder.serve("bar", "1.0.0", pubspec: {
+          "dependencies": {
+            "shared-dep": "any",
+            "bar-dep": "any"
+          }
+        });
+        builder.serve("shared-dep", "1.0.0");
+        builder.serve("bar-dep", "1.0.0");
+      });
 
       d.appDir({
         "foo": "any",