Only generate summaries in tests when necessary

pkg/analyzer/test/src/summary/pub_summary_test.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.
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary/pub_summary.dart';
@@ skipping 236 matching lines @@
       linkedHashA = packageA.linkedHash;
       linkedHashB = packageB.linkedHash;
       _assertFileExists(folderA, 'linked_spec_$linkedHashA.ds');
       _assertFileExists(folderB, 'linked_spec_$linkedHashB.ds');
     }
 
     // Session 2.
     // Use DartSdk with a different API signature.
     // Different linked bundles should be created.
     {
-      MockSdk sdk = new MockSdk(
-          buildSummaries: false, resourceProvider: resourceProvider);
+      MockSdk sdk = new MockSdk(resourceProvider: resourceProvider);
       sdk.updateUriFile('dart:math', (String content) {
         return content + '  class NewMathClass {}';
       });
       context.sourceFactory = new SourceFactory(<UriResolver>[
         new DartUriResolver(sdk),
         resourceResolver,
         new PackageMapUriResolver(resourceProvider, {
           'aaa': [libFolderA],
           'bbb': [libFolderB],
         })
@@ skipping 1109 matching lines @@
     }
   }
 
   static PackageBundle _getBundleByPackageName(
       Map<PubPackage, PackageBundle> bundles, String name) {
     PubPackage package =
         bundles.keys.singleWhere((package) => package.name == name);
     return bundles[package];
   }
 }