Updated tests/compiler/* to use new library syntax.

tests/compiler/dart2js/constant_folding_test.dart

 // 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.
 // Test constant folding on numbers.
 
-#import("compiler_helper.dart");
+import 'compiler_helper.dart';
 
 const String NUMBER_FOLDING = """
 void main() {
   var a = 4;
   var b = 3;
   print(a + b);
 }
 """;
 
 const String NEGATIVE_NUMBER_FOLDING = """
@@ skipping 25 matching lines @@
 
   regexp = const RegExp(r'null == b');
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp(r'4 === c');
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp("'foo' === d");
   Expect.isTrue(regexp.hasMatch(generated));
 }