Clean up hints after a new hint was introduced

pkg/analyzer/lib/src/generated/sdk.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;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisOptions;
-import 'package:analyzer/src/generated/source.dart'
-    show ContentCache, Source, UriKind;
+import 'package:analyzer/src/generated/source.dart' show Source;
 
 /**
  * A function used to create a new DartSdk with the given [options]. If the
  * passed [options] are `null`, then default options are used.
  */
 typedef DartSdk SdkCreator(AnalysisOptions options);
 
 /**
  * A Dart SDK installed in a specified location.
  */
@@ skipping 423 matching lines @@
     _platforms |= DART2JS_PLATFORM;
   }
 
   /**
    * Record that this library can be run on the VM.
    */
   void setVmLibrary() {
     _platforms |= VM_PLATFORM;
   }
 }