Fix summarization of trailing `dynamic` type arguments.

pkg/analyzer/test/src/summary/resynthesize_test.dart

Index: pkg/analyzer/test/src/summary/resynthesize_test.dart
diff --git a/pkg/analyzer/test/src/summary/resynthesize_test.dart b/pkg/analyzer/test/src/summary/resynthesize_test.dart
index e977fa6e5e87f3bce66e3e144d0c88855b873b48..667f3cd4c6d7173398a62f121b60a49326920312 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_test.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_test.dart
@@ -1348,7 +1348,19 @@ void set x(value) {}''');
     checkLibrary('void set x(int value) {} set y(value) {}');
   }
 
-  test_type_arguments_explicit() {
+  test_type_arguments_explicit_dynamic_dynamic() {
+    checkLibrary('Map<dynamic, dynamic> m;');
+  }
+
+  test_type_arguments_explicit_dynamic_int() {
+    checkLibrary('Map<dynamic, int> m;');
+  }
+
+  test_type_arguments_explicit_String_dynamic() {
+    checkLibrary('Map<String, dynamic> m;');
+  }
+
+  test_type_arguments_explicit_String_int() {
     checkLibrary('Map<String, int> m;');
   }