Allow surrogates in string literals.

tests/language/string_literals_test.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file

[siva, 2016/09/23 14:47:32]

2016

+// 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 "package:expect/expect.dart";
+
+main() {
+  var expect = new String.fromCharCodes([
+    0, 0x0a, 0x0d, 0x7f, 0xff, 0xffff, 0xd800, 0xdc00, 0xdbff, 0xdfff
+  ]);
+  test(string) {
+    Expect.equals(expect, string);
+  }
+
+  // Plain escapes of code points.
+  test("\x00\x0a\x0d\x7f\xff\uffff\u{10000}\u{10ffff}");
+  test("""\x00\x0a\x0d\x7f\xff\uffff\u{10000}\u{10ffff}""");
+  test('\x00\x0a\x0d\x7f\xff\uffff\u{10000}\u{10ffff}');
+  test('''\x00\x0a\x0d\x7f\xff\uffff\u{10000}\u{10ffff}''');
+  // Plain escapes of individual code units.
+  test("\x00\x0a\x0d\x7f\xff\uffff\ud800\udc00\udbff\udfff");
+  test("""\x00\x0a\x0d\x7f\xff\uffff\ud800\udc00\udbff\udfff""");
+  test('\x00\x0a\x0d\x7f\xff\uffff\ud800\udc00\udbff\udfff');
+  test('''\x00\x0a\x0d\x7f\xff\uffff\ud800\udc00\udbff\udfff''');
+  // Insert newline into multiline string.
+  test("""\x00
+\x0d\x7f\xff\uffff\ud800\udc00\udbff\udfff""");
+  test('''\x00
+\x0d\x7f\xff\uffff\ud800\udc00\udbff\udfff''');
+  // Extract code points from multi-character escape string.
+  test("\x00\x0a\x0d\x7f\xff\uffff"
+       "${"\u{10000}"[0]}${"\u{10000}"[1]}"
+       "${"\u{10FFFF}"[0]}${"\u{10FFFF}"[1]}");
+  test("\x00\x0a\x0d\x7f\xff\uffff" +
+      "\ud800" + "\udc00\udbff" + "\udfff");
+  // Single line string over multiple lines with newlines inside interpolation.
+  test("\x00\x0a\x0d\x7f\xff${
+           ""
+       }\uffff\ud800\udc00\udbff\udfff");
+}