Compute ElementImpl.hashCode using location.

pkg/analyzer/lib/src/dart/element/element.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.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1783 matching lines @@
     _enclosingElement = element as ElementImpl;
     _cachedLocation = null;
     _cachedHashCode = null;
   }
 
   @override
   int get hashCode {
     // TODO: We might want to re-visit this optimization in the future.
     // We cache the hash code value as this is a very frequently called method.
     if (_cachedHashCode == null) {
-      int hashIdentifier = identifier.hashCode;
-      Element enclosing = enclosingElement;
-      if (enclosing != null) {
-        _cachedHashCode = hashIdentifier + enclosing.hashCode;
-      } else {
-        _cachedHashCode = hashIdentifier;
-      }
+      _cachedHashCode = location.hashCode;
     }
     return _cachedHashCode;
   }
 
   /**
    * Return an identifier that uniquely identifies this element among the
    * children of this element's parent.
    */
   String get identifier => name;
 
@@ skipping 2984 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }