Delete dart_backend from compiler.

pkg/compiler/lib/src/compiler.dart

 // Copyright (c) 2012, 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.compiler_base;
 
 import 'dart:async' show EventSink, Future;
 
 import '../compiler_new.dart' as api;
 import 'cache_strategy.dart' show CacheStrategy;
 import 'closure.dart' as closureMapping show ClosureTask;
 import 'common/backend_api.dart' show Backend;
 import 'common/codegen.dart' show CodegenWorkItem;
 import 'common/names.dart' show Selectors;
 import 'common/names.dart' show Identifiers, Uris;
 import 'common/registry.dart' show EagerRegistry, Registry;
 import 'common/resolution.dart'
     show
         ParsingContext,
         Resolution,
         ResolutionWorkItem,
         ResolutionImpact,
         Target;
 import 'common/tasks.dart' show CompilerTask, GenericTask, Measurer;
 import 'common/work.dart' show ItemCompilationContext, WorkItem;
 import 'common.dart';
 import 'compile_time_constants.dart';
 import 'constants/values.dart';
 import 'core_types.dart' show CoreClasses, CoreTypes;
-import 'dart_backend/dart_backend.dart' as dart_backend;
 import 'dart_types.dart' show DartType, DynamicType, InterfaceType, Types;
 import 'deferred_load.dart' show DeferredLoadTask;
 import 'diagnostics/code_location.dart';
 import 'diagnostics/diagnostic_listener.dart' show DiagnosticReporter;
 import 'diagnostics/invariant.dart' show REPORT_EXCESS_RESOLUTION;
 import 'diagnostics/messages.dart' show Message, MessageTemplate;
 import 'dump_info.dart' show DumpInfoTask;
 import 'elements/elements.dart';
 import 'elements/modelx.dart' show ErroneousElementX;
 import 'enqueue.dart'
@@ skipping 254 matching lines @@
     if (options.verbose) {
       progress = new Stopwatch()..start();
     }
 
     // TODO(johnniwinther): Separate the dependency tracking from the enqueuing
     // for global dependencies.
     globalDependencies = new GlobalDependencyRegistry(this);
 
     if (makeBackend != null) {
       backend = makeBackend(this);
-    } else if (options.emitJavaScript) {
+    } else {
       js_backend.JavaScriptBackend jsBackend = new js_backend.JavaScriptBackend(
           this,
           generateSourceMap: options.generateSourceMap,
           useStartupEmitter: options.useStartupEmitter,
           useNewSourceInfo: options.useNewSourceInfo);
       backend = jsBackend;
-    } else {
-      backend = new dart_backend.DartBackend(this, options.strips,
-          multiFile: options.dart2dartMultiFile);
-      if (options.dumpInfo) {
-        throw new ArgumentError('--dump-info is not supported for dart2dart.');
-      }
     }
 
     if (options.dumpInfo && options.useStartupEmitter) {
       throw new ArgumentError(
           '--dump-info is not supported with the fast startup emitter');
     }
 
     tasks = [
       dietParser =
           new DietParserTask(options, idGenerator, backend, reporter, measurer),
@@ skipping 1846 matching lines @@
   _ElementScanner(this.scanner);
   void scanLibrary(LibraryElement library) => scanner.scanLibrary(library);
   void scanUnit(CompilationUnitElement unit) => scanner.scan(unit);
 }
 
 class _EmptyEnvironment implements Environment {
   const _EmptyEnvironment();
 
   String valueOf(String key) => null;
 }