Fix handling of CRLF line endings in Script::GetSnippet.

tests/lib/mirrors/method_mirror_source_line_ending_test.dart

+// Copyright (c) 2014, 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.
+
+import "dart:mirrors";
+import "package:expect/expect.dart";
+
+import "method_mirror_source_line_ending_lf.dart";
+import "method_mirror_source_line_ending_cr.dart";
+import "method_mirror_source_line_ending_crlf.dart";
+
+main() {
+  String sourceOf(Function f) => (reflect(f) as ClosureMirror).function.source;
+
+  // Source does not cross line breaks.
+  Expect.stringEquals('oneLineLF(x) => x;', sourceOf(oneLineLF));
+  Expect.stringEquals('oneLineCR(x) => x;', sourceOf(oneLineCR));
+  Expect.stringEquals('oneLineCRLF(x) => x;', sourceOf(oneLineCRLF));
+
+  // Source includes line breaks.
+  Expect.stringEquals('multiLineLF(y) {\n  return y + 1;\n}',
+                      sourceOf(multiLineLF));
+  Expect.stringEquals('multiLineCR(y) {\r  return y + 1;\r}',
+                      sourceOf(multiLineCR));
+  Expect.stringEquals('multiLineCRLF(y) {\r\n  return y + 1;\r\n}',
+                      sourceOf(multiLineCRLF));
+
+  // First and last characters separated from middle by line breaks.
+  Expect.stringEquals('a\n(){\n}', sourceOf(a));
+  Expect.stringEquals('b\r(){\r}', sourceOf(b));
+  Expect.stringEquals('c\r\n(){\r\n}', sourceOf(c));
+}