Fix hints reported by analyzer.

pkg/compiler/lib/src/js_backend/backend_helpers.dart

 // Copyright (c) 2015, 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 dart2js.js_backend.helpers;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers, Uris;
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
@@ skipping 188 matching lines @@
 
   ConstructorElement get symbolValidatedConstructor {
     return _symbolValidatedConstructor ??= _findConstructor(
         symbolImplementationClass, symbolValidatedConstructorSelector.name);
   }
 
   // TODO(johnniwinther): Make these private.
   // TODO(johnniwinther): Split into _findHelperFunction and _findHelperClass
   // and add a check that the element has the expected kind.
   Element _findHelper(String name) => _find(jsHelperLibrary, name);
-  FunctionElement _findHelperFunction(String name) =>
-      _find(jsHelperLibrary, name);
   Element _findAsyncHelper(String name) => _find(asyncLibrary, name);
   Element _findInterceptor(String name) => _find(interceptorsLibrary, name);
   Element _find(LibraryElement library, String name) {
     Element element = library.implementation.findLocal(name);
     assert(invariant(library, element != null,
         message: "Element '$name' not found in '${library.canonicalUri}'."));
     return element;
   }
 
   Element findCoreHelper(String name) =>
@@ skipping 654 matching lines @@
   }
 
   MethodElement get toStringForNativeObject {
     return _findHelper('toStringForNativeObject');
   }
 
   MethodElement get hashCodeForNativeObject {
     return _findHelper('hashCodeForNativeObject');
   }
 }