Add interfaces for a new compiler API.

tests/compiler/dart2js/deferred_custom_element_test.dart

Index: tests/compiler/dart2js/deferred_custom_element_test.dart
diff --git a/tests/compiler/dart2js/deferred_custom_element_test.dart b/tests/compiler/dart2js/deferred_custom_element_test.dart
index 9cbf87fa14dab133841797795608978055f7ef14..1fa5d120cb4d66040a144d9c31afbd97aff01d7b 100644
--- a/tests/compiler/dart2js/deferred_custom_element_test.dart
+++ b/tests/compiler/dart2js/deferred_custom_element_test.dart
@@ -6,32 +6,13 @@
 // 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:expect/expect.dart';
-import "package:async_helper/async_helper.dart";
-import 'memory_source_file_helper.dart';
-import "dart:async";
-
-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 mainOutputUnit = compiler.deferredLoadTask.mainOutputUnit;