Small steps towards deferred loading.

pkg/front_end/lib/src/fasta/builder/prefix_builder.dart

Index: pkg/front_end/lib/src/fasta/builder/prefix_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/builder/prefix_builder.dart b/pkg/front_end/lib/src/fasta/builder/prefix_builder.dart
index 861075fffec0326590cac8aa82a7092b65e189d9..de6b474dade28d15325626a539828d10e9a25bcc 100644
--- a/pkg/front_end/lib/src/fasta/builder/prefix_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/prefix_builder.dart
@@ -13,7 +13,9 @@ class PrefixBuilder extends Builder {
 
   final LibraryBuilder parent;
 
-  PrefixBuilder(this.name, LibraryBuilder parent, int charOffset)
+  final bool deferred;
+
+  PrefixBuilder(this.name, this.deferred, LibraryBuilder parent, int charOffset)
       : parent = parent,
         super(parent, charOffset, parent.fileUri);