Replace Backend with JavaScriptBackend.

pkg/compiler/lib/src/common/resolution.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.common.resolution;
 
 import '../common.dart';
 import '../compile_time_constants.dart';
 import '../constants/expressions.dart' show ConstantExpression;
 import '../constants/values.dart' show ConstantValue;
 import '../core_types.dart' show CommonElements;
 import '../elements/resolution_types.dart' show ResolutionDartType, Types;
 import '../elements/elements.dart'
     show
         AstElement,
         ClassElement,
         Element,
         ExecutableElement,
         FunctionElement,
         FunctionSignature,
         LibraryElement,
         MetadataAnnotation,
         MethodElement,
         ResolvedAst,
         TypedefElement;
 import '../elements/entities.dart';
 import '../enqueue.dart' show ResolutionEnqueuer;
 import '../id_generator.dart';
+import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../mirrors_used.dart';
 import '../options.dart' show CompilerOptions;
 import '../parser/element_listener.dart' show ScannerOptions;
 import '../parser/parser_task.dart';
 import '../scanner/scanner_task.dart';
 import '../patch_parser.dart';
 import '../resolution/resolution.dart';
 import '../tree/tree.dart' show Send, TypeAnnotation;
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/world_impact.dart' show WorldImpact;
@@ skipping 172 matching lines @@
   bool isProxyConstant(ConstantValue value);
 }
 
 /// A container of commonly used dependencies for tasks that involve parsing.
 abstract class ParsingContext {
   factory ParsingContext(
       DiagnosticReporter reporter,
       ParserTask parser,
       ScannerTask scanner,
       PatchParserTask patchParser,
-      Backend backend) = _ParsingContext;
+      JavaScriptBackend backend) = _ParsingContext;
 
   DiagnosticReporter get reporter;
   ParserTask get parser;
   ScannerTask get scanner;
   PatchParserTask get patchParser;
 
   /// Use [patchParser] directly instead.
   @deprecated
   void parsePatchClass(ClassElement cls);
 
   /// Use [parser] and measure directly instead.
   @deprecated
   measure(f());
 
   /// Get the [ScannerOptions] to scan the given [element].
   ScannerOptions getScannerOptionsFor(Element element);
 }
 
 class _ParsingContext implements ParsingContext {
   final DiagnosticReporter reporter;
   final ParserTask parser;
   final ScannerTask scanner;
   final PatchParserTask patchParser;
-  final Backend backend;
+  final JavaScriptBackend backend;
 
   _ParsingContext(
       this.reporter, this.parser, this.scanner, this.patchParser, this.backend);
 
   @override
   measure(f()) => parser.measure(f);
 
   @override
   void parsePatchClass(ClassElement cls) {
     patchParser.measure(() {
       if (cls.isPatch) {
         patchParser.parsePatchClassNode(cls);
       }
     });
   }
 
   @override
   ScannerOptions getScannerOptionsFor(Element element) => new ScannerOptions(
       canUseNative: backend.canLibraryUseNative(element.library));
 }