Barback transforms now pass through the primary input by default.

pkg/barback/test/package_graph/lazy_transformer_test.dart

Index: pkg/barback/test/package_graph/lazy_transformer_test.dart
diff --git a/pkg/barback/test/package_graph/lazy_transformer_test.dart b/pkg/barback/test/package_graph/lazy_transformer_test.dart
index c43c9f1633100be987a4fb78bb939771c73126bb..1c96e02c375a589e1645356ad20d0c0cf54890ae 100644
--- a/pkg/barback/test/package_graph/lazy_transformer_test.dart
+++ b/pkg/barback/test/package_graph/lazy_transformer_test.dart
@@ -25,7 +25,7 @@ main() {
     var transformer = new LazyRewriteTransformer("blub", "blab");
     initGraph(["app|foo.blub"], {"app": [[transformer]]});
     updateSources(["app|foo.blub"]);
-    expectAllAssets(["app|foo.blab"]);
+    expectAllAssets(["app|foo.blub", "app|foo.blab"]);
     buildShouldSucceed();
     expect(transformer.numRuns, completion(equals(1)));
   });