Eliminate old style import from language tests

tests/language/library12.dart

 // Copyright (c) 2011, 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("library12.dart");
+library library12.dart;
 
-#import("library11.dart");
+import "library11.dart";
 class Library12 {
   Library12(this.fld);
   Library12.other(fld, multiplier) {
     this.fld = fld*multiplier;
   }
   func() {
     return 2;
   }
   var fld;
   static static_func() {
@@ skipping 15 matching lines @@
 }
 
 interface Library12Interface {
   Library12 addObjects(Library12 value1, Library12 value2);
 }
 
 const int top_level12 = 10;
 top_level_func12() {
   return 20;
 }