Have setters use strict -> like methods

pkg/dev_compiler/test/codegen/language/abstract_method_test.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.
 
 import "package:expect/expect.dart";
 
 // Checks that abstract instance methods are correctly resolved.
 
 int get length => throw "error: top-level getter called";
 set height(x) { throw "error: top-level setter called"; }
 width() { throw "error: top-level function called"; }
 
 abstract class A {
   int get length;     // Abstract instance getter.
-  set height(x);      // Abstract instance setter.
+  set height(int x);  // Abstract instance setter.
   int width();        // Abstract instance method.
 
   // Must resolve to non-abstract length getter in subclass.
   get useLength => length;
   // Must resolve to non-abstract height setter in subclass.
   setHeight(x) => height = x;
   // Must resolve to non-abstract width() method in subclass.
   useWidth() => width();
 }
 
 class A1 extends A {
   int length;  // Implies a length getter.
   int height;  // Implies a height setter.
   int width() => 345;
   A1(this.length);
 }
 
 main() {
   var a = new A1(123);
   Expect.equals(123, a.useLength);
   a.setHeight(234);
   Expect.equals(234, a.height);
   Expect.equals(345, a.useWidth());
   print([a.useLength, a.height, a.useWidth()]);
 }