Fix interpretation of string contents after interpolation expressions.

tests/language/regress_23046_test.dart

 // Copyright (c) 2015, 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.
 
-// This is a regression test for http://dartbug.com/22723.
-
 import "package:expect/expect.dart";
 
-class A {
-  final x;
+// Make sure the logic for skipping the initial quotes in a string isn't
+// re-triggered after an interpolation expression.
 
-  @NoInline()
-  A({this.x: "foo"}) {
-    Expect.equals("foo", x.toString());
-  }
-}
-
-class C extends A {
-  C(foobar) { }
-}
+const String x = '$y"';
+const String y = 'foo';
+const Map m = const { x: 0, y: 1 };
 
 main() {
-  var c = new C(499);
-  Expect.equals("foo", c.x.toString());
+  Expect.equals(x, 'foo"');
+  Expect.equals(m.length, 2);
 }
-