Handle multiline interpolated strings in line-based scanner.

dart/tests/language/string_interpolation_newline_test.dart

Index: dart/tests/language/string_interpolation_newline_test.dart
diff --git a/dart/tests/language/string_interpolation_newline_test.dart b/dart/tests/language/string_interpolation_newline_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..91ad04f5242c3fa404de3f6219cb583e58bab3db
--- /dev/null
+++ b/dart/tests/language/string_interpolation_newline_test.dart
@@ -0,0 +1,20 @@
+// 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.
+
+/// Test of newlines in interpolated strings.
+
+main() {
+  String expected = '[[{{}: {}}]]';
+  String a = "${ [ "${ [ '${ { '${ { } }' : { } } }' ] }" ] }";
+  String b = "${ [ "${ [ '${ { '${
+      { } }' : { } } }' ] }" ] }";
+  String c = "${ [ "${ [ '${ { '${
+      {
+      } }' : {
+      } } }' ] }" ] }";
+  if (expected != a) throw 'expecteda: $expected != $a';
+  if (a != b) throw 'ab: $a != $b';
+  if (b != c) throw 'bc: $b != $c';
+  print('$a$b$c');
+}