Deprecate PrefixElement.importedLibraries.

pkg/analyzer/test/src/summary/resynthesize_test.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 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 628 matching lines @@
         expect(resynthesized.field, isNotNull, reason: '$desc field');
         compareFieldElements(
             resynthesized.field, original.field, '$desc field');
       }
     }
   }
 
   void comparePrefixElements(PrefixElementImpl resynthesized,
       PrefixElementImpl original, String desc) {
     compareElements(resynthesized, original, desc);
-    // TODO(paulberry): test _importedLibraries.
   }
 
   void comparePropertyAccessorElements(
       PropertyAccessorElementImpl resynthesized,
       PropertyAccessorElementImpl original,
       String desc) {
     // TODO(paulberry): do I need to worry about
     // MultiplyInheritedPropertyAccessorElementImpl?
     compareExecutableElements(resynthesized, original, desc);
     expect(resynthesized.variable, isNotNull);
@@ skipping 2485 matching lines @@
       fail('Unexpectedly tried to get unlinked summary for $uri');
     }
     return serializedUnit;
   }
 
   @override
   bool hasLibrarySummary(String uri) {
     return true;
   }
 }