Add interfaces for a new compiler API.

tests/compiler/dart2js/deferred_follow_constant_dependencies_test.dart

 // Copyright (c) 2014, 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 that constants depended on by other constants are correctly deferred.
 
-import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/constants/values.dart';
+import 'package:compiler/src/dart2jslib.dart';
 import 'package:expect/expect.dart';
-import 'memory_source_file_helper.dart';
-
-
-class FakeOutputStream<T> extends EventSink<T> {
-  void add(T event) {}
-  void addError(T event, [StackTrace stackTrace]) {}
-  void close() {}
-}
+import 'memory_compiler.dart';
 
 void main() {
-  Uri script = currentDirectory.resolveUri(Platform.script);
-  Uri libraryRoot = script.resolve('../../../sdk/');
-  Uri packageRoot = script.resolve('./packages/');
-
-  var provider = new MemorySourceFileProvider(MEMORY_SOURCE_FILES);
-  var handler = new FormattingDiagnosticHandler(provider);
-
-  Compiler compiler = new Compiler(provider.readStringFromUri,
-                                   (name, extension) => new FakeOutputStream(),
-                                   handler.diagnosticHandler,
-                                   libraryRoot,
-                                   packageRoot,
-                                   [],
-                                   {});
+  Compiler compiler = compilerFor(MEMORY_SOURCE_FILES);
   asyncTest(() => compiler.run(Uri.parse('memory:main.dart')).then((_) {
     var outputUnitForElement = compiler.deferredLoadTask.outputUnitForElement;
     var outputUnitForConstant = compiler.deferredLoadTask.outputUnitForConstant;
     var mainOutputUnit = compiler.deferredLoadTask.mainOutputUnit;
     var lib =
         compiler.libraryLoader.lookupLibrary(Uri.parse("memory:lib.dart"));
     var backend = compiler.backend;
     List<ConstantValue> allConstants = [];
 
     addConstantWithDependendencies(ConstantValue c) {
@@ skipping 30 matching lines @@
   print(lib.L);
 }
 """, "lib.dart": """
 class C {
   final a;
   const C(this.a);
 }
 
 const L = const {"cA": const C(const {"cB": "cC"})};
 """,};