Don't allow escaping newlines in single line strings.

dart/tests/language/src/StringEscape3NegativeTestHelper.dart

Index: dart/tests/language/src/StringEscape3NegativeTestHelper.dart
diff --git a/dart/tests/language/src/StringEscape3NegativeTestHelper.dart b/dart/tests/language/src/StringEscape3NegativeTestHelper.dart
new file mode 100644
index 0000000000000000000000000000000000000000..584b43357acee418d3ccbd148e3f21b671974599
--- /dev/null
+++ b/dart/tests/language/src/StringEscape3NegativeTestHelper.dart
@@ -0,0 +1,7 @@
+// 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.
+
+// An empty library.

[Lasse Reichstein Nielsen, 2012/01/26 19:19:19]

I can see that. Say what we are testing (i.e., how it can fail).

[ahe, 2012/01/26 19:30:28]

Ditto.

+
+#library('empty');