Fix summary handling of invalid annotations of the form `@a.b.c`.

pkg/analyzer/lib/src/summary/summarize_ast.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library serialization.summarize_ast;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/type.dart' show DartType;
@@ skipping 35 matching lines @@
   _ConstExprSerializer(
       this.visitor, this.localClosureIndexMap, this.parameterNames);
 
   @override
   bool isParameterName(String name) {
     return parameterNames?.contains(name) ?? false;
   }
 
   @override
   void serializeAnnotation(Annotation annotation) {
+    Identifier name = annotation.name;
+    EntityRefBuilder constructor;
+    if (name is PrefixedIdentifier && annotation.constructorName == null) {
+      constructor =
+          serializeConstructorRef(null, name.prefix, null, name.identifier);
+    } else {
+      constructor = serializeConstructorRef(
+          null, annotation.name, null, annotation.constructorName);
+    }
     if (annotation.arguments == null) {
-      assert(annotation.constructorName == null);
-      serialize(annotation.name);
+      references.add(constructor);
+      operations.add(UnlinkedExprOperation.pushReference);
     } else {
-      Identifier name = annotation.name;
-      EntityRefBuilder constructor;
-      if (name is PrefixedIdentifier && annotation.constructorName == null) {
-        constructor =
-            serializeConstructorRef(null, name.prefix, null, name.identifier);
-      } else {
-        constructor = serializeConstructorRef(
-            null, annotation.name, null, annotation.constructorName);
-      }
       serializeInstanceCreation(constructor, annotation.arguments);
     }
   }
 
   @override
   EntityRefBuilder serializeConstructorRef(DartType type, Identifier typeName,
       TypeArgumentList typeArguments, SimpleIdentifier name) {
     EntityRefBuilder typeBuilder = serializeType(type, typeName, typeArguments);
     if (name == null) {
       return typeBuilder;
@@ skipping 1340 matching lines @@
 /**
  * A [_TypeParameterScope] is a [_Scope] which defines [_ScopedTypeParameter]s.
  */
 class _TypeParameterScope extends _Scope {
   /**
    * Get the number of [_ScopedTypeParameter]s defined in this
    * [_TypeParameterScope].
    */
   int get length => _definedNames.length;
 }