Fix instance compound assignment.

tests/language/src/InstanceCompoundAssignmentOperatorTest.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 // Test correct instance compound assignment operator.
 
 class A {
   A() : f = 2 {}
   var f;
+  operator [](index) => f;
+  operator []=(index, value) => f = value;
 }
 
 
 class B {
   B() : _a = new A(), count = 0 {}
   get a() {
     count++;
     return _a;
   }
   var _a;
   var count;
 }
 
 
-class InstanceCompoundAssignmentOperatorTest {
-  static void testMain() {
-    B b = new B();
-    Expect.equals(0, b.count);
-    Expect.equals(2, b.a.f);
-    Expect.equals(1, b.count);
-    var o = b.a;
-    Expect.equals(2, b.count);
-    b.a.f = 1;
-    Expect.equals(3, b.count);
-    b.a.f += 1;
-    Expect.equals(4, b.count);
-  }
+main() {
+  B b = new B();
+  Expect.equals(0, b.count);
+  Expect.equals(2, b.a.f);
+  Expect.equals(1, b.count);
+  var o = b.a;

[Lasse Reichstein Nielsen, 2012/04/10 12:31:13]

How about also counting gets/sets of 'f' (i.e., make a test where 'f' has a
getter and setter that counts too - or just a property g that gets/sets f and
counts).
It's important that we only read b.a once in b.a.f += 1, but also important that
we only read 'f' once and only sets it once.

[floitsch, 2012/04/10 15:51:00]

Done.

+  Expect.equals(2, b.count);
+  b.a.f = 1;
+  Expect.equals(3, b.count);
+  Expect.equals(1, b._a.f);
+  b.a.f += 1;
+  Expect.equals(4, b.count);
+  Expect.equals(2, b._a.f);
+
+  b.count = 0;
+  b._a.f = 2;
+  Expect.equals(0, b.count);
+  Expect.equals(2, b.a[0]);
+  Expect.equals(1, b.count);
+  o = b.a;
+  Expect.equals(2, b.count);
+  b.a[0] = 1;
+  Expect.equals(3, b.count);
+  Expect.equals(1, b._a.f);
+  b.a[0] += 1;
+  Expect.equals(4, b.count);
+  Expect.equals(2, b._a.f);
 }
-main() {
-  InstanceCompoundAssignmentOperatorTest.testMain();
-}