Fix dominatedUsers for phis.

tests/language/type_propagation_phi_test.dart

Index: tests/language/type_propagation_phi_test.dart
diff --git a/tests/language/type_propagation_in_for_update_test.dart b/tests/language/type_propagation_phi_test.dart
similarity index 53%
copy from tests/language/type_propagation_in_for_update_test.dart
copy to tests/language/type_propagation_phi_test.dart
index 2a41e0cdbea7bb648a47d2db5f3d72f4a00fd67f..b64cfa767b76e579170af7706196f9ff7e2ef734 100644
--- a/tests/language/type_propagation_in_for_update_test.dart
+++ b/tests/language/type_propagation_phi_test.dart
@@ -4,23 +4,18 @@
 // Check that phi type computation in the Dart2Js compiler does the
 // correct thing.
 
-bar() => 'foo';
+bar() => 490;
+bar2() => 0;
 
-main() {
-  Expect.throws(foo1);
-  Expect.throws(foo2);
-}
-
-foo1() {
-  var a = bar();
-  for (;; a = 1 + a) {
-    if (a != 'foo') return;
-  }
+foo(b) {
+  var x = bar();
+  var x2 = x;
+  if (b) x2 = bar2();
+  var x3 = 9 + x;  // Guarantees that x is a number. Dart2js propagated the
+                   // type information back to the phi (for x2).
+  return x2 + x3;
 }
 
-foo2() {
-  var a = bar();
-  for (;; a = 1 + a) {
-    if (a != 'foo') break;
-  }
+main() {
+  Expect.equals(499, foo(true));
 }