anchor.diff:    // From dart:_internal
   
     late final ClassEntity symbolImplementationClass =
  -      _findClass(internalLibrary, 'Symbol')!;
  +      _findClass(internalLibrary, 'Symbol');
   
     /// Used to annotate items that have the keyword "native".
     late final ClassEntity externalNameClass =
  -      _findClass(internalLibrary, 'ExternalName')!;
  +      _findClass(internalLibrary, 'ExternalName');
   
     InterfaceType get externalNameType => _getRawType(externalNameClass);
   
     // From dart:_js_embedded_names
   
  -  late final ClassEntity jsGetNameEnum = _findClass(
  -      _env.lookupLibrary(Uris.dart__js_shared_embedded_names, required: true),
  -      'JsGetName')!;
  +  late final ClassEntity jsGetNameEnum =
  +      _findClass(sharedEmbeddedNamesLibrary, 'JsGetName');
   
     /// Returns `true` if [member] is a "foreign helper", that is, a member whose
     /// semantics is defined synthetically and not through Dart code.
  
positive.code:   // From package:js
  
    late final ClassEntity? jsAnnotationClass1 =
        _findClass(packageJsLibrary, 'JS', required: false);
  
    late final ClassEntity? jsAnonymousClass1 =
        _findClass(packageJsLibrary, '_Anonymous', required: false);
  
    // From dart:_js_annotations
  
    late final ClassEntity? jsAnnotationClass2 =
        _findClass(dartJsAnnotationsLibrary, 'JS', required: false);
  
    late final ClassEntity? jsAnonymousClass2 =
        _findClass(dartJsAnnotationsLibrary, '_Anonymous', required: false);
  
    /// Returns `true` if [cls] is a @JS() annotation.
    ///
  
negative.code:     return _createInterfaceType(streamClass, [elementType]);
    }
  
    ClassEntity _findClass(LibraryEntity? library, String name) {
      return _env.lookupClass(library!, name, required: true)!;
    }
  
    ClassEntity? _findClassOrNull(LibraryEntity? library, String name) {
      if (library == null) return null;
      return _env.lookupClass(library, name, required: false);
    }
  
    T? _findLibraryMember<T extends MemberEntity>(
  