Add interfaces for a new compiler API.

pkg/compiler/lib/src/dart2jslib.dart

Index: pkg/compiler/lib/src/dart2jslib.dart
diff --git a/pkg/compiler/lib/src/dart2jslib.dart b/pkg/compiler/lib/src/dart2jslib.dart
index fcbeecbcef09863a4a08cf944b717d203eff62ae..14dad6a3b6d3b22f3fb9d8219467a47ddc45968e 100644
--- a/pkg/compiler/lib/src/dart2jslib.dart
+++ b/pkg/compiler/lib/src/dart2jslib.dart
@@ -9,7 +9,7 @@ import 'dart:collection' show Queue;
 import 'dart:profiler' show
     UserTag;
 
-import '../compiler.dart' as api;
+import '../compiler_new.dart' as api;
 import 'cache_strategy.dart';
 import 'closure.dart' as closureMapping;
 import 'compile_time_constants.dart';
@@ -43,6 +43,7 @@ import 'library_loader.dart'
          LibraryLoaderTask,
          LoadedLibraries;
 import 'mirrors_used.dart' show MirrorUsageAnalyzerTask;
+import 'null_compiler_output.dart';
 import 'native/native.dart' as native;
 import 'ordered_typeset.dart';
 import 'patch_parser.dart';