Don't use SDK summaries with embedders (#26448).

pkg/analyzer/lib/src/generated/sdk_io.dart

 // Copyright (c) 2014, 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.sdk_io;
 
 import 'dart:collection';
 import 'dart:io';
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 396 matching lines @@
         // Fall through to return the default.
       }
     }
     return _sdkVersion;
   }
 
   @override
   List<String> get uris => _libraryMap.uris;
 
   /**
+   * Whether an SDK summary should be used.
+   */
+  bool get useSummary => _useSummary;
+
+  /**
    * Specify whether SDK summary should be used.
    */
   void set useSummary(bool use) {
     if (_analysisContext != null) {
       throw new StateError(
           'The "useSummary" flag cannot be changed after context creation.');
     }
     _useSummary = use;
   }
 
@@ skipping 256 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;
   }
 }