Correctly skip if-null expressions.

tests/language/regress_26543_1_test.dart

Index: tests/language/regress_26543_1_test.dart
diff --git a/tests/lib/mirrors/private_class_field_other.dart b/tests/language/regress_26543_1_test.dart
similarity index 50%
copy from tests/lib/mirrors/private_class_field_other.dart
copy to tests/language/regress_26543_1_test.dart
index 85238b6009d14d7ee0a4b500df90e863f8896fa3..8c425ded3a50970fb3d3727ef81389c9bacb1d93 100644
--- a/tests/lib/mirrors/private_class_field_other.dart
+++ b/tests/language/regress_26543_1_test.dart
@@ -1,9 +1,14 @@
 // Copyright (c) 2016, 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.
+// BSD-style license that can be found in the LICENSE file. 
+
+// Regression test for issue 26543
 
 class C {
-  static var _privateField = 42;
+  var x;
+  C() : x = null ?? <int, int>{} {}
 }
 
-get privateFieldSymbolInOther => #_privateField;
+main() {
+  print(new C());
+}