Add tests for problem with newline encoding in multiline strings.

tests/language/multiline_newline_lf.dart

Index: tests/language/multiline_newline_lf.dart
diff --git a/tests/compiler/dart2js_extra/deferred_split_lib2.dart b/tests/language/multiline_newline_lf.dart
similarity index 64%
copy from tests/compiler/dart2js_extra/deferred_split_lib2.dart
copy to tests/language/multiline_newline_lf.dart
index d690e311ecee452f767aa8ea630e510b8c780bbc..48b6901890087a1582fa230afe5c168179a53cd6 100644
--- a/tests/compiler/dart2js_extra/deferred_split_lib2.dart
+++ b/tests/language/multiline_newline_lf.dart
@@ -2,8 +2,14 @@
 // 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.
 
-// Deferred library loaded by deferred_split_test.dart
+library multiline_newline_lf;
 
-import 'deferred_split_lib1.dart';
+const constantMultilineString = """
+a
+b
+""";
 
-createA() => new A();
+var nonConstantMultilineString = """
+a
+b
+""";