Add support for compiling Dart via the FE in dart2js.

pkg/compiler/lib/src/frontend_strategy.dart

 // Copyright (c) 2017, 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.
 
 library dart2js.frontend_strategy;
 
+import '../compiler_new.dart' as api;
 import 'common.dart';
 import 'common_elements.dart';
 import 'common/backend_api.dart';
 import 'common/tasks.dart';
 import 'elements/entities.dart';
 import 'elements/types.dart';
 import 'environment.dart';
 import 'enqueue.dart';
 import 'js_backend/backend.dart';
 import 'js_backend/backend_usage.dart';
@@ skipping 12 matching lines @@
 import 'universe/world_builder.dart';
 import 'universe/world_impact.dart';
 
 /// Strategy pattern that defines the connection between the input format and
 /// the resolved element model.
 abstract class FrontendStrategy {
   /// Creates library loader task for this strategy.
   LibraryLoaderTask createLibraryLoader(
       ResolvedUriTranslator uriTranslator,
       ScriptLoader scriptLoader,
+      api.CompilerInput compilerInput,
       ElementScanner scriptScanner,
       LibraryDeserializer deserializer,
       PatchResolverFunction patchResolverFunc,
       PatchParserTask patchParser,
       Environment environment,
       DiagnosticReporter reporter,
       Measurer measurer);
 
   /// Returns the [ElementEnvironment] for the element model used in this
   /// strategy.
@@ skipping 77 matching lines @@
     if (_nativeBasicData == null) {
       _nativeBasicData = nativeBasicDataBuilder.close(elementEnvironment);
       assert(
           _nativeBasicData != null,
           failedAt(NO_LOCATION_SPANNABLE,
               "NativeBasicData has not been computed yet."));
     }
     return _nativeBasicData;
   }
 }