Issue 1229. Report error for using unary plus operator.

tests/language/src/UnaryPlusNegativeTest.dart

Index: tests/language/src/UnaryPlusNegativeTest.dart
diff --git a/tests/language/src/UnaryPlusNegativeTest.dart b/tests/language/src/UnaryPlusNegativeTest.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9f68d8ad7eb089d5a2a39d45f6fefcf5c3f8b156
--- /dev/null
+++ b/tests/language/src/UnaryPlusNegativeTest.dart
@@ -0,0 +1,10 @@
+// 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.
+
+// There is no unary plus operator in Dart.
+
+main() {
+  var a = 1;
+  var b = +a;
+}