Add handleNoVariableInitializer event.

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 897a754608819c9a83e200cb0d84845179b09326..174b4def0bba095c59db0730559c365392b766f6 100644
--- a/pkg/front_end/lib/src/fasta/parser/listener.dart
+++ b/pkg/front_end/lib/src/fasta/parser/listener.dart
@@ -352,10 +352,17 @@ class Listener {
 
   void beginVariableInitializer(Token token) {}
 
+  /// Handle the end of a variable initializer. Substructures:
+  /// - Initializer expression.
   void endVariableInitializer(Token assignmentOperator) {
     logEvent("VariableInitializer");
   }
 
+  /// Used when a variable has no initializer.
+  void handleNoVariableInitializer(Token token) {
+    logEvent("NoVariableInitializer");
+  }
+
   void beginInitializer(Token token) {}
 
   void endInitializer(Token token) {