Revert "Add support for metadata on type variables to Fasta parser."

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 c900ea4a553230df6dfdc4a95c325d3e3a471592..3e74225ed889dbdf8244d9ef002a03666bfd1752 100644
--- a/pkg/front_end/lib/src/fasta/parser/listener.dart
+++ b/pkg/front_end/lib/src/fasta/parser/listener.dart
@@ -526,11 +526,6 @@ class Listener {
 
   void beginMetadata(Token token) {}
 
-  /// Handle the end of a metadata annotation.  Substructures:
-  /// - Identifier
-  /// - Type arguments
-  /// - Constructor name (only if [periodBeforeName] is not `null`)
-  /// - Arguments
   void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
     logEvent("Metadata");
   }
@@ -719,7 +714,6 @@ class Listener {
 
   /// Handle the end of a type formal parameter (e.g. "X extends Y").
   /// Substructures:
-  /// - Metadata
   /// - Name (identifier)
   /// - Type bound
   void endTypeVariable(Token token, Token extendsOrSuper) {