Fix hints

pkg/analyzer/lib/src/generated/incremental_resolver.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 engine.incremental_resolver;
 
 import 'dart:collection';
 import 'dart:math' as math;
 
 import 'package:analyzer/src/services/lint.dart';
@@ skipping 619 matching lines @@
 
   /**
    * Given that the comparison is to begin with the given [element], capture
    * the enclosing elements that might be used while performing the comparison.
    */
   void _captureEnclosingElements(Element element) {
     Element parent =
         element is CompilationUnitElement ? element : element.enclosingElement;
     while (parent != null) {
       if (parent is CompilationUnitElement) {
-        _enclosingUnit = parent as CompilationUnitElement;
+        _enclosingUnit = parent;
         _enclosingLibrary = element.library;
       } else if (parent is ClassElement) {
         if (_enclosingClass == null) {
-          _enclosingClass = parent as ClassElement;
+          _enclosingClass = parent;
         }
       } else if (parent is FunctionTypeAliasElement) {
         if (_enclosingAlias == null) {
-          _enclosingAlias = parent as FunctionTypeAliasElement;
+          _enclosingAlias = parent;
         }
       } else if (parent is ParameterElement) {
         if (_enclosingParameter == null) {
-          _enclosingParameter = parent as ParameterElement;
+          _enclosingParameter = parent;
         }
       }
       parent = parent.enclosingElement;
     }
   }
 
   void _gatherElements(Element element) {
     _ElementsGatherer gatherer = new _ElementsGatherer(this);
     element.accept(gatherer);
     // TODO(scheglov) what if a change in a directive?
@@ skipping 1147 matching lines @@
   @override
   String toString() => name;
 }
 
 class _TokenPair {
   final _TokenDifferenceKind kind;
   final Token oldToken;
   final Token newToken;
   _TokenPair(this.kind, this.oldToken, this.newToken);
 }