[Fasta] include source code in dill

pkg/kernel/lib/transformations/closure/mock.dart

Index: pkg/kernel/lib/transformations/closure/mock.dart
diff --git a/pkg/kernel/lib/transformations/closure/mock.dart b/pkg/kernel/lib/transformations/closure/mock.dart
index 95a4cbdcd7f53d74f2f656f6b33cf1d1c83e65d6..031501a5ca2fc28e7ee019e48f73e04085f641c5 100644
--- a/pkg/kernel/lib/transformations/closure/mock.dart
+++ b/pkg/kernel/lib/transformations/closure/mock.dart
@@ -191,6 +191,6 @@ Class mockUpContext(CoreTypes coreTypes, Program program) {
       name: "mock", classes: [contextClass])..fileUri = fileUri;
   program.libraries.add(mock);
   mock.parent = program;
-  program.uriToSource[mock.fileUri] = new Source(<int>[0], "");
+  program.uriToSource[mock.fileUri] = new Source(<int>[0], const <int>[]);
   return contextClass;
 }