Don't require Transformer methods to return Futures.

sdk/lib/_internal/pub/test/transformer/supports_a_transformer_that_doesnt_return_futures_test.dart

Index: sdk/lib/_internal/pub/test/transformer/supports_a_transformer_that_doesnt_return_futures_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/can_use_consume_primary_test.dart b/sdk/lib/_internal/pub/test/transformer/supports_a_transformer_that_doesnt_return_futures_test.dart
similarity index 62%
copy from sdk/lib/_internal/pub/test/transformer/can_use_consume_primary_test.dart
copy to sdk/lib/_internal/pub/test/transformer/supports_a_transformer_that_doesnt_return_futures_test.dart
index 9b41b2bbc5905412e31e2c3d02224973d5b1ff64..e4ac4ef7e5fb32a25f00338dac7180fbe2c41902 100644
--- a/sdk/lib/_internal/pub/test/transformer/can_use_consume_primary_test.dart
+++ b/sdk/lib/_internal/pub/test/transformer/supports_a_transformer_that_doesnt_return_futures_test.dart
@@ -13,25 +13,25 @@ import 'dart:async';
 
 import 'package:barback/barback.dart';
 
-class RewriteTransformer extends Transformer {
+class RewriteTransformer extends Transformer implements DeclaringTransformer {
   RewriteTransformer.asPlugin();
 
-  String get allowedExtensions => '.txt';
+  bool isPrimary(AssetId id) => id.extension == '.txt';
 
-  Future apply(Transform transform) {
-    transform.consumePrimary();
-    return transform.primaryInput.readAsString().then((contents) {
-      var id = transform.primaryInput.id.changeExtension(".out");
-      var asset = new Asset.fromString(id, "\$contents.out");
-      transform.addOutput(asset);
-    });
+  void apply(Transform transform) {
+    transform.addOutput(new Asset.fromString(
+        transform.primaryInput.id, "new contents"));
+  }
+
+  void declareOutputs(DeclaringTransform transform) {
+    transform.declareOutput(transform.primaryId);
   }
 }
 """;
 
 main() {
   initConfig();
-  integration("a transform can use consumePrimary", () {
+  integration("supports a transformer that doesn't return futures", () {
     d.dir(appPath, [
       d.pubspec({
         "name": "myapp",
@@ -48,8 +48,7 @@ main() {
     createLockFile('myapp', pkg: ['barback']);
 
     pubServe();
-    requestShouldSucceed("foo.out", "foo.out");
-    requestShould404("foo.txt");
+    requestShouldSucceed("foo.txt", "new contents");
     endPubServe();
   });
 }