Make isEmpty a getter.

tests/compiler/dart2js_extra/no_such_method_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.
 
 class NoSuchMethodInfo {
   Object receiver;
   String name;
   List args;
   NoSuchMethodInfo(Object r, String m, List a)
     : receiver = r, name = m, args = a;
@@ skipping 10 matching lines @@
   }
 }
 
 // Used for the setter case.
 NoSuchMethodInfo topLevelInfo;
 
 main() {
   A a = new A();
   var info = a.foo();
   Expect.equals('foo', info.name);
-  Expect.isTrue(info.args.isEmpty());
+  Expect.isTrue(info.args.isEmpty);
   Expect.isTrue(info.receiver === a);
 
   info = a.foo(2);
   Expect.equals('foo', info.name);
   Expect.isTrue(info.args.length == 1);
   Expect.isTrue(info.args[0] === 2);
   Expect.isTrue(info.receiver === a);
 
   info = a.bar;
   Expect.equals('get:bar', info.name);
   Expect.isTrue(info.args.length == 0);
   Expect.isTrue(info.receiver === a);
 
   a.bar = 2;
   info = topLevelInfo;
   Expect.equals('set:bar', info.name);
   Expect.isTrue(info.args.length == 1);
   Expect.isTrue(info.args[0] === 2);
   Expect.isTrue(info.receiver === a);
 }