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

tests/compiler/dart2js/parameter_phi_elimination_test.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.
 
 // Regression test. Failed due to trying to detach an HLocal twice.
 
 // VMOptions=--enable_asserts
 
-#import("compiler_helper.dart");
+import 'compiler_helper.dart';
 
 const String SOURCE = r"""
 bool baz(int a, int b) {
   while (a == b || a < b) {
     a = a + b;
   }
   return a == b;
 }
 """;
 
 
 main() {
   compile(SOURCE, entry: "baz");
 }