Add type inference logic for map literals

pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart

Index: pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
diff --git a/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart b/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
index c7bfd35f644324e177df6b6a0d9c9e2b9177abfc..1284f53371e229af7eb32f5eda4624fef5f785a1 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
@@ -168,6 +168,12 @@ class TypeInferenceListener
   void listLiteralExit(ListLiteral expression, DartType inferredType) =>
       debugExpressionExit("listLiteral", expression, inferredType);
 
+  bool mapLiteralEnter(MapLiteral expression, DartType typeContext) =>
+      debugExpressionEnter("mapLiteral", expression, typeContext);
+
+  void mapLiteralExit(MapLiteral expression, DartType typeContext) =>
+      debugExpressionExit("mapLiteral", expression, typeContext);
+
   bool methodInvocationEnter(
           MethodInvocation expression, DartType typeContext) =>
       debugExpressionEnter("methodInvocation", expression, typeContext);