fix #43, remove => workaround

lib/src/codegen/js_codegen.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:collection' show HashSet, HashMap, SplayTreeSet;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/src/generated/ast.dart' hide ConstantEvaluator;
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 3545 matching lines @@
     var rules = new StrongTypeSystemImpl();
     var codegen =
         new JSCodegenVisitor(compiler, rules, library, _extensionTypes, fields);
     var module = codegen.emitLibrary(unit);
     var out = compiler.getOutputPath(library.source.uri);
     var flags = compiler.options;
     var serverUri = flags.serverMode
         ? Uri.parse('http://${flags.host}:${flags.port}/')
         : null;
     return writeJsLibrary(module, out, compiler.inputBaseDir, serverUri,
-        emitSourceMaps: options.emitSourceMaps,
-        arrowFnBindThisWorkaround: options.arrowFnBindThisWorkaround);
+        emitSourceMaps: options.emitSourceMaps);
   }
 }
 
 /// Choose a canonical name from the library element.
 /// This never uses the library's name (the identifier in the `library`
 /// declaration) as it doesn't have any meaningful rules enforced.
 String jsLibraryName(LibraryElement library) => canonicalLibraryName(library);
 
 /// Shorthand for identifier-like property names.
 /// For now, we emit them as strings and the printer restores them to
 /// identifiers if it can.
 // TODO(jmesserly): avoid the round tripping through quoted form.
 JS.LiteralString _propertyName(String name) => js.string(name, "'");
 
 // TODO(jacobr): we would like to do something like the following
 // but we don't have summary support yet.
 // bool _supportJsExtensionMethod(AnnotatedNode node) =>
 //    _getAnnotation(node, "SupportJsExtensionMethod") != null;
 
 /// A special kind of element created by the compiler, signifying a temporary
 /// variable. These objects use instance equality, and should be shared
 /// everywhere in the tree where they are treated as the same variable.
 class TemporaryVariableElement extends LocalVariableElementImpl {
   TemporaryVariableElement.forNode(Identifier name) : super.forNode(name);
 
   int get hashCode => identityHashCode(this);
   bool operator ==(Object other) => identical(this, other);
 }