Update an out-of-date test.

tests/compiler/dart2js/dart_backend_test.dart

 // Copyright (c) 2012, 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.
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import "package:async_helper/async_helper.dart";
 import 'parser_helper.dart';
 import 'mock_compiler.dart';
 import '../../../sdk/lib/_internal/compiler/compiler.dart';
@@ skipping 369 matching lines @@
   a = getA();
   topfoo();
   mylib.topfoo();
 }
 ''';
   var expectedResult =
     'topfoo(){}'
     'class A{foo(){}}'
     'A_topfoo(){var x=5;}'
     'class A_A{num foo(){}A_A.fromFoo(){}A myliba;List<A_A> mylist;}'
-    'A getA()=>null;'
+    'A getA(){}'
     'main(){var a=new A();a.foo();var b=new A_A.fromFoo();b.foo();'
         'var GREATVAR=b.myliba;b.mylist;a=getA();A_topfoo();topfoo();}';
   testDart2DartWithLibrary(mainSrc, librarySrc,
       continuation: (String result) { Expect.equals(expectedResult, result); });
 }
 
 testClassExtendsWithArgs() {
   testDart2Dart('main(){new B<Object>();}'
     'class A<T extends Object>{}'
     'class B<T extends Object> extends A<T>{}');
@@ skipping 330 matching lines @@
   testStaticAccessIoLib();
   testLocalFunctionPlaceholder();
   testMinification();
   testClosureLocalsMinified();
   testParametersMinified();
   testDeclarationTypePlaceholders();
   testPlatformLibraryMemberNamesAreFixed();
   testConflictsWithCoreLib();
   testUnresolvedNamedConstructor();
 }