Fix usage of UNKNOWN/CONFLICTING types for union.

tests/language/field_optimization2_test.dart

Index: tests/language/field_optimization2_test.dart
diff --git a/tests/language/implicit_closure2_test.dart b/tests/language/field_optimization2_test.dart
similarity index 58%
copy from tests/language/implicit_closure2_test.dart
copy to tests/language/field_optimization2_test.dart
index 40c47bec801509d574a197da88cd97f931eeae78..d8b6ec3c2e908fcce428e3106849d8425ff842ce 100644
--- a/tests/language/implicit_closure2_test.dart
+++ b/tests/language/field_optimization2_test.dart
@@ -2,21 +2,23 @@
 // 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 B {
-  foo(i) => 499 + i;
-}
+// Dart test program to test type-based optimization on fields.
 
-class A {
-  var b;
-  A() : b = new B();
 
-  foo(i) { return (() => b.foo(i))(); }
+class A {
+  var x;
+  A() : x = new B();
+  foo() {
+    x++;
+  }
 }
 
+class B {
+  operator +(other) => 498;
+}
 main() {
   var a = new A();
-  Expect.equals(510, a.foo(11));
-  var f = a.foo;
-  Expect.equals(521, f(22));
+  a.foo();
+  a.foo();
+  Expect.equals(499, a.x);
 }
-