Fix documentation for Listener.endLibraryName.

pkg/front_end/lib/src/fasta/parser/listener.dart

Index: pkg/front_end/lib/src/fasta/parser/listener.dart
diff --git a/pkg/front_end/lib/src/fasta/parser/listener.dart b/pkg/front_end/lib/src/fasta/parser/listener.dart
index 3e74225ed889dbdf8244d9ef002a03666bfd1752..cb167d722ba49201efe2176777e9afa6629d04df 100644
--- a/pkg/front_end/lib/src/fasta/parser/listener.dart
+++ b/pkg/front_end/lib/src/fasta/parser/listener.dart
@@ -468,6 +468,7 @@ class Listener {
   void beginLibraryName(Token token) {}
 
   /// Handle the end of a library directive.  Substructures:
+  /// - Metadata
   /// - Library name (a qualified identifier)
   void endLibraryName(Token libraryKeyword, Token semicolon) {
     logEvent("LibraryName");