Add interfaces for a new compiler API.

tests/compiler/dart2js/deferred_load_graph_segmentation_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.
 
 // Test of the graph segmentation algorithm used by deferred loading
 // to determine which elements can be deferred and which libraries
 // much be included in the initial download (loaded eagerly).
 
+import 'package:async_helper/async_helper.dart';
+import 'package:compiler/src/dart2jslib.dart';
+import 'package:compiler/src/deferred_load.dart';
 import 'package:expect/expect.dart';
-import "package:async_helper/async_helper.dart";
-import 'memory_source_file_helper.dart';
-import "dart:async";
-
-import 'package:compiler/src/dart2jslib.dart'
-       as dart2js;
-
-import 'package:compiler/src/deferred_load.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((_) {
     lookupLibrary(name) {
       return compiler.libraryLoader.lookupLibrary(Uri.parse(name));
     }
 
-    var main = compiler.mainApp.find(dart2js.Compiler.MAIN);
+    var main = compiler.mainApp.find(Compiler.MAIN);
     Expect.isNotNull(main, "Could not find 'main'");
     compiler.deferredLoadTask.onResolutionComplete(main);
 
     var outputUnitForElement = compiler.deferredLoadTask.outputUnitForElement;
 
     var mainOutputUnit = compiler.deferredLoadTask.mainOutputUnit;
     var backend = compiler.backend;
     var classes = backend.emitter.neededClasses;
     var inputElement = classes.where((e) => e.name == 'InputElement').single;
     var lib1 = lookupLibrary("memory:lib1.dart");
@@ skipping 106 matching lines @@
 
 bar1() {
   return "hello";
 }
 
 bar2() {
   return 2;
 }
 """,
 };