fix call to get current source - fixes #24509

pkg/analysis_server/lib/src/services/completion/local_reference_contributor.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 services.completion.contributor.dart.local;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' as protocol
     show Element, ElementKind;
@@ skipping 338 matching lines @@
  * that contains the completion offset to the [CompilationUnit].
  */
 class _LocalVisitor extends LocalDeclarationVisitor {
   final DartCompletionRequest request;
   final OpType optype;
   int privateMemberRelevance = DART_RELEVANCE_DEFAULT;
 
   _LocalVisitor(this.request, int offset, this.optype) : super(offset) {
     includeLocalInheritedTypes = !optype.inStaticMethodBody;
     if (request.replacementLength > 0) {
-      var contents = request.source.contents;
+      var contents = request.context.getContents(request.source);
       if (contents != null &&
           contents.data != null &&
           contents.data.startsWith('_', request.replacementOffset)) {
         // If user typed identifier starting with '_'
         // then do not suppress the relevance of private members
         privateMemberRelevance = null;
       }
     }
   }
 
@@ skipping 216 matching lines @@
   bool _isVoid(TypeName returnType) {
     if (returnType != null) {
       Identifier id = returnType.name;
       if (id != null && id.name == 'void') {
         return true;
       }
     }
     return false;
   }
 }