dart2js: check for the full getter/setter prefixes (fix #23828)

tests/compiler/dart2js_extra/23828_test.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.
 
+// Regression test for http://dartbug.com/23828/
+// Used to fail when methods contain a name starting with `get`
 import 'package:expect/expect.dart';
 
-class SuperClass {
-  final field = 0;
-  noSuchMethod(_) => 42;
-}
+confuse(x) { return x; return x; }
 
-class Class extends SuperClass {
-  m() {
-    super.field = 87; /// 01: static type warning
-  }
+class MA {
+  noSuchMethod(i) => Expect.equals(i.positionalArguments.length, 1);
 }
 
 main() {
-  new Class().m(); /// 01: continued
-}
+  confuse(new MA()).getFoo('a');
+}