Revert "Remove Registry from registerMetadataConstant" and "Serialize metadata"

pkg/compiler/lib/src/native/enqueue.dart

Index: pkg/compiler/lib/src/native/enqueue.dart
diff --git a/pkg/compiler/lib/src/native/enqueue.dart b/pkg/compiler/lib/src/native/enqueue.dart
index e8f3340234730e701a3894b121d3b5153ed97948..63b601d898b3c905a0ce96b43c5b7e28f7af1b92 100644
--- a/pkg/compiler/lib/src/native/enqueue.dart
+++ b/pkg/compiler/lib/src/native/enqueue.dart
@@ -318,7 +318,7 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
       // TODO(sra): Better validation of the constant.
       if (fields.length != 1 || fields.single is! StringConstantValue) {
         reporter.internalError(
-            annotation, 'Annotations needs one string: ${annotation}');
+            annotation, 'Annotations needs one string: ${annotation.node}');
       }
       StringConstantValue specStringConstant = fields.single;
       String specString = specStringConstant.toDartString().slowToString();
@@ -326,7 +326,7 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
         name = specString;
       } else {
         reporter.internalError(
-            annotation, 'Too many JSName annotations: ${annotation}');
+            annotation, 'Too many JSName annotations: ${annotation.node}');
       }
     }
     return name;