Prepare for development branch by updating externally-used API.

pkg/front_end/lib/src/fasta/dill/dill_loader.dart

Index: pkg/front_end/lib/src/fasta/dill/dill_loader.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_loader.dart b/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
index 1401159e716b61736dc18e894ce6b8a9640c56c1..b8537da9d2caddddad36a36cc7d434ac0bbf364a 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
@@ -26,7 +26,7 @@ class DillLoader extends Loader<Library> {
     for (Library library in program.libraries) {
       if (filter == null || filter(library.importUri)) {
         libraries.add(library);
-        DillLibraryBuilder builder = read(library.importUri);
+        DillLibraryBuilder builder = read(library.importUri, -1);
         builder.library = library;
         builders.add(builder);
       }
@@ -34,8 +34,6 @@ class DillLoader extends Loader<Library> {
     return builders;
   }
 
-  DillLibraryBuilder read(Uri uri, [Uri fileUri]) => super.read(uri, fileUri);
-
   Future<Null> buildOutline(DillLibraryBuilder builder) async {
     builder.library.classes.forEach(builder.addClass);
     builder.library.procedures.forEach(builder.addMember);