Get rid of support for string interpolation in #import strings.

tests/vm/dart/mysrc/test2.dart

Index: tests/vm/dart/mysrc/test2.dart
===================================================================
--- tests/vm/dart/mysrc/test2.dart	(revision 11672)
+++ tests/vm/dart/mysrc/test2.dart	(working copy)
@@ -1,13 +0,0 @@
-// Copyright (c) 2012, 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.
-
-#library('test2.dart');
-
-#source('../$SRC/test2a.dart');
-
-int test2() {
-  var result = test2a();
-  Expect.equals(2, result);
-  return result;
-}