anchor.diff:  import '../js_backend/runtime_types_codegen.dart'
       show ClassChecks, ClassFunctionType, Substitution, TypeCheck;
   import '../js_emitter/sorter.dart';
  +import '../options.dart';
   import '../util/util.dart' show Setlet;
   
   import 'code_emitter_task.dart' show CodeEmitterTask, Emitter;
  
positive.code:             checkedClass, _namer.operatorIs(checkedClass), js('1'));
        }
        Substitution substitution = check.substitution;
        if (substitution != null) {
          jsAst.Expression body =
              _getSubstitutionCode(emitterTask.emitter, substitution);
          result.addSubstitution(
  
negative.code:   final RuntimeTypesChecks _rtiChecks;
    final RuntimeTypesEncoder _rtiEncoder;
    final _TypeContainedInOutputUnitVisitor _outputUnitVisitor;
  
    CompilerOptions get _options => emitterTask.options;
  
    RuntimeTypeGenerator(this._commonElements, this._outputUnitData,
        this.emitterTask, this._namer, this._rtiChecks, this._rtiEncoder)
  