Fix for parsing generic function types with Fasta.

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 633ef962780ee115d46986eae80436965622d9c5..2ac5422a647e06f6e4f21c6b7c6eaa3dc15a4e19 100644
--- a/pkg/front_end/lib/src/fasta/parser/listener.dart
+++ b/pkg/front_end/lib/src/fasta/parser/listener.dart
@@ -680,6 +680,12 @@ class Listener {
     logEvent("NoName");
   }
 
+  /// Handle the end of a generic function type declaration.
+  ///
+  /// Substructures:
+  /// - Return type
+  /// - Type variables
+  /// - Formal parameters
   void handleFunctionType(Token functionToken, Token endToken) {
     logEvent("FunctionType");
   }