AbstractDartSdk should not return its linked bundle if 'useSummary' is false.

pkg/analyzer/lib/src/dart/sdk/sdk.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 analyzer.src.generated.sdk2;
 
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io' as io;
 
@@ skipping 137 matching lines @@
     } on FormatException catch (exception, stackTrace) {
       AnalysisEngine.instance.logger.logInformation(
           "Failed to create URI: $path",
           new CaughtException(exception, stackTrace));
     }
     return null;
   }
 
   @override
   PackageBundle getLinkedBundle() {
-    bool strongMode = _analysisOptions?.strongMode ?? false;
-    _sdkBundle ??= getSummarySdkBundle(strongMode);
-    return _sdkBundle;
+    if (_useSummary) {
+      bool strongMode = _analysisOptions?.strongMode ?? false;
+      _sdkBundle ??= getSummarySdkBundle(strongMode);
+      return _sdkBundle;
+    }
+    return null;
   }
 
   String getRelativePathFromFile(File file);
 
   @override
   SdkLibrary getSdkLibrary(String dartUri) => libraryMap.getLibrary(dartUri);
 
   /**
    * Return the [PackageBundle] for this SDK, if it exists, or `null` otherwise.
    * This method should not be used outside of `analyzer` and `analyzer_cli`
@@ skipping 695 matching lines @@
     SdkLibrariesReader_LibraryBuilder libraryBuilder =
         new SdkLibrariesReader_LibraryBuilder(_useDart2jsPaths);
     // If any syntactic errors were found then don't try to visit the AST
     // structure.
     if (!errorListener.errorReported) {
       unit.accept(libraryBuilder);
     }
     return libraryBuilder.librariesMap;
   }
 }