Compute export namespaces for DILL libraries.

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

Index: pkg/front_end/lib/src/fasta/source/source_library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
index b24abaa6eb47d2027d029fb9115266c7d04a50bf..a8e3ffadedf073c991db0d061f441f5c1a08134e 100644
--- a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
@@ -436,25 +436,6 @@ abstract class SourceLibraryBuilder<T extends TypeBuilder, R>
     }
   }
 
-  /// Returns true if the export scope was modified.
-  bool addToExportScope(String name, Builder member) {
-    if (name.startsWith("_")) return false;
-    if (member is PrefixBuilder) return false;
-    Map<String, Builder> map =
-        member.isSetter ? exports.setters : exports.local;
-    Builder existing = map[name];
-    if (existing == member) return false;
-    if (existing != null) {
-      Builder result =
-          buildAmbiguousBuilder(name, existing, member, -1, isExport: true);
-      map[name] = result;
-      return result != existing;
-    } else {
-      map[name] = member;
-    }
-    return true;
-  }
-
   int resolveTypes(_) {
     int typeCount = types.length;
     for (T t in types) {