Use memory compiler in compiler_helper.dart.

tests/compiler/dart2js/bad_loop_test.dart

 // Copyright (c) 2013, 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.
 
 import 'package:expect/expect.dart';
 import 'memory_source_file_helper.dart';
 import "package:async_helper/async_helper.dart";
 
 import 'package:compiler/compiler.dart'
        show Diagnostic;
+import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/old_to_new_api.dart';
 
 main() {
   Uri script = currentDirectory.resolveUri(Platform.script);
   Uri libraryRoot = script.resolve('../../../sdk/');
   Uri packageRoot = script.resolve('./packages/');
 
   var provider = new MemorySourceFileProvider(MEMORY_SOURCE_FILES);
   int warningCount = 0;
   int errorCount = 0;
@@ skipping 10 matching lines @@
       throw 'unexpected diagnostic $kind: $message';
     }
   }
 
   Compiler compiler = new Compiler(
       new LegacyCompilerInput(provider.readStringFromUri),
       new LegacyCompilerOutput(),
       new LegacyCompilerDiagnostics(diagnosticHandler),
       libraryRoot,
       packageRoot,
-      ['--analyze-only'],
+      [Flags.analyzeOnly],
       {});
   asyncTest(() => compiler.run(Uri.parse('memory:main.dart')).then((_) {
     Expect.isTrue(compiler.compilationFailed);
     Expect.equals(5, errorCount);
     Expect.equals(1, warningCount);
   }));
 }
 
 const Map MEMORY_SOURCE_FILES = const {
   'main.dart': """
 main() {
   for (var x, y in []) {
   }
 
   for (var x = 10 in []) {
   }
 
   for (x.y in []) { // Also causes a warning "x unresolved".
   }
 
   for ((){}() in []) {
   }
 
   for (1 in []) {
   }
 }
 """
 };