Ensure metadata on imports/exports is resolved for serialization.

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index cf4e21525616fef7efa12a76c5696ab39252ac36..189c7d0db64b2e6016740093f1cc643d770940cb 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -904,6 +904,14 @@ abstract class Compiler implements LibraryLoaderListener {
           world.addToWorkList(loadLibrary);
         }
       }
+      for (MetadataAnnotation metadata in import.metadata) {

[Siggi Cherem (dart-lang), 2016/08/18 15:28:17]

how about only doing this if serialization is turned on? (otherwise it seems
like extra unnecessary work)

[Johnni Winther, 2016/08/19 08:16:53]

Done.

+        metadata.ensureResolved(resolution);
+      }
+    });
+    library.exports.forEach((ExportElement export) {
+      for (MetadataAnnotation metadata in export.metadata) {
+        metadata.ensureResolved(resolution);
+      }
     });
   }