Scrub all non-identifier characters from JavaScript class names

pkg/compiler/lib/src/js_backend/namer.dart

 // Copyright (c) 2011, 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 js_backend.namer;
 
 import 'dart:collection' show HashMap;
 
 import 'package:js_runtime/shared/embedded_names.dart' show JsGetName;
 
@@ skipping 1268 matching lines @@
     if (!name.contains(r'$')) {
       // Prepend $$. The result must not coincide with an annotated name.
       name = '\$\$$name';
     }
     return name;
   }
 
   /// Returns a proposed name for the given typedef or class [element].
   /// The returned id is guaranteed to be a valid JavaScript identifier.
   String _proposeNameForType(Entity element) {
-    return element.name.replaceAll('+', '_');
+    return element.name.replaceAll(_nonIdentifierRE, '_');
   }
 
+  static RegExp _nonIdentifierRE = new RegExp(r'[^A-Za-z0-9_$]');
+
   /// Returns a proposed name for the given top-level or static member
   /// [element]. The returned id is guaranteed to be a valid JavaScript
   /// identifier.
   String _proposeNameForMember(MemberEntity element) {
     if (element.isConstructor) {
       return _proposeNameForConstructor(element);
     } else if (element.enclosingClass != null) {
       ClassEntity enclosingClass = element.enclosingClass;
       return '${enclosingClass.name}_${element.name}';
     }
@@ skipping 935 matching lines @@
   void addSuggestion(String original, String suggestion) {
     assert(!_suggestedNames.containsKey(original));
     _suggestedNames[original] = suggestion;
   }
 
   bool hasSuggestion(String original) => _suggestedNames.containsKey(original);
   bool isSuggestion(String candidate) {
     return _suggestedNames.containsValue(candidate);
   }
 }