Issue 27244. Add 'isDeprecated' to HoverInformation.

pkg/analysis_server/lib/src/computer/computer_hover.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 computer.hover;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart'
     show HoverInformation;
 import 'package:analysis_server/src/computer/computer_overrides.dart';
 import 'package:analysis_server/src/utilities/documentation.dart';
@@ skipping 38 matching lines @@
         // variable, if synthetic accessor
         if (element is PropertyAccessorElement) {
           PropertyAccessorElement accessor = element;
           if (accessor.isSynthetic) {
             element = accessor.variable;
           }
         }
         // description
         hover.elementDescription = element.toString();
         hover.elementKind = element.kind.displayName;
+        hover.isDeprecated = element.isDeprecated;
         // not local element
         if (element.enclosingElement is! ExecutableElement) {
           // containing class
           ClassElement containingClass =
               element.getAncestor((e) => e is ClassElement);
           if (containingClass != null) {
             hover.containingClassDescription = containingClass.displayName;
           }
           // containing library
           LibraryElement library = element.library;
@@ skipping 53 matching lines @@
         Element interfaceClass = superElement.enclosingElement;
         return removeDartDocDelimiters(rawDoc) +
             '\n\nCopied from `${interfaceClass.displayName}`.';
       }
     }
     return null;
   }
 
   static _safeToString(obj) => obj?.toString();
 }