Fix summarization of closures in toplevel variable declarations in part files.

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

 // Copyright (c) 2015, 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 test.src.serialization.elements_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 1617 matching lines @@
 
   test_closure_executable_with_return_type_from_closure() {
     checkLibrary('''
 f() {
   print(() {});
   print(() => () => 0);
 }
 ''');
   }
 
+  test_closure_in_variable_declaration_in_part() {
+    addSource('/a.dart', 'part of lib; final f = (int i) => i.toDouble();');
+    checkLibrary('''
+library lib;
+part "a.dart";
+''');
+  }
+
   test_const_invalid_field_const() {
     variablesWithNotConstInitializers.add('f');
     checkLibrary(
         r'''
 class C {
   static const f = 1 + foo();
 }
 int foo() => 42;
 ''',
         allowErrors: true);
@@ skipping 3047 matching lines @@
       fail('Unexpectedly tried to get unlinked summary for $uri');
     }
     return serializedUnit;
   }
 
   @override
   bool hasLibrarySummary(String uri) {
     return true;
   }
 }