Use unitMember/classMember/parameter names instead of offsets in index.

pkg/analysis_server/lib/src/services/search/search_engine_internal.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 analysis_server.src.services.search.search_engine_internal;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/services/correction/source_range.dart';
 import 'package:analysis_server/src/services/index/index.dart';
@@ skipping 243 matching lines @@
     AstNode node = element.computeNode();
     AstNode enclosingNode = node?.getAncestor(isRootNode);
     enclosingNode?.accept(visitor);
     return visitor.matches;
   }
 
   Future<List<SearchMatch>> _searchReferences_Parameter(
       ParameterElement parameter) async {
     List<SearchMatch> matches = <SearchMatch>[];
     matches.addAll(await _searchReferences(parameter));
-    matches.addAll(await _searchReferences_Local(
-        parameter,
-        (n) =>
-            n is ConstructorDeclaration ||
-            n is MethodDeclaration ||
-            n is FunctionExpression));
+    matches.addAll(await _searchReferences_Local(parameter, (AstNode node) {
+      AstNode parent = node.parent;
+      return parent is ClassDeclaration || parent is CompilationUnit;
+    }));
     return matches;
   }
 
   Future<List<SearchMatch>> _searchReferences_Prefix(
       PrefixElement element) async {
     List<SearchMatch> matches = <SearchMatch>[];
     LibraryElement libraryElement = element.library;
     Source librarySource = libraryElement.source;
     AnalysisContext context = libraryElement.context;
     for (CompilationUnitElement unitElement in libraryElement.units) {
@@ skipping 121 matching lines @@
           }
         } else if (isSet) {
           kind = MatchKind.WRITE;
         }
       }
       _addMatch(node, kind);
     }
   }
 
   void _addMatch(AstNode node, MatchKind kind) {
-    bool isQualified = node is SimpleIdentifier && node.isQualified;
+    bool isQualified = node.parent is Label;
     matches.add(new SearchMatch(context, libraryUri, unitUri, kind,
         rangeNode(node), true, isQualified));
   }
 }