Handle complicated imports.

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

Index: pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart b/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
index 30a175648d611007afeaf56d179ffad4fd6783cc..56b8c79519bb6d8ae735e9948fe856fd5f9908fc 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
@@ -101,12 +101,15 @@ class DillLibraryBuilder extends LibraryBuilder<KernelTypeBuilder, Library> {
     return internalError("Not implemented yet.");
   }
 
-  void addToScope(String name, Builder member) {
+  @override
+  void addToScope(String name, Builder member, int charOffset, bool isImport) {
     internalError("Not implemented yet.");
   }
 
-  KernelInvalidTypeBuilder buildAmbiguousBuilder(
-      String name, Builder builder, Builder other, int charOffset) {
+  @override
+  Builder buildAmbiguousBuilder(
+      String name, Builder builder, Builder other, int charOffset,
+      {bool isExport: false, bool isImport: false}) {
     return new KernelInvalidTypeBuilder(name, charOffset, fileUri);
   }