Handle complicated imports.

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

Index: pkg/front_end/lib/src/fasta/builder/library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/builder/library_builder.dart b/pkg/front_end/lib/src/fasta/builder/library_builder.dart
index 11d5ecf53f0bcc4d7b83759854517ca78c746aa5..76057b4a1586f24f4c80499893c5937a8530f99d 100644
--- a/pkg/front_end/lib/src/fasta/builder/library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/library_builder.dart
@@ -86,10 +86,11 @@ abstract class LibraryBuilder<T extends TypeBuilder, R> extends Builder {
 
   bool addToExportScope(String name, Builder member);
 
-  void addToScope(String name, Builder member);
+  void addToScope(String name, Builder member, int charOffset, bool isImport);
 
   Builder buildAmbiguousBuilder(
-      String name, Builder builder, Builder other, int charOffset);
+      String name, Builder builder, Builder other, int charOffset,
+      {bool isExport: false, bool isImport: false});
 
   int finishStaticInvocations() => 0;