anchor.diff:     * typedefs and implicitly through type annotations in checked mode.
      */
     Set<FunctionType> checkedFunctionTypes;
  -
  -  Map<ClassElement, Set<FunctionType>> checkedGenericFunctionTypes =
  -      new Map<ClassElement, Set<FunctionType>>();
  -
  -  Set<FunctionType> checkedNonGenericFunctionTypes =
  -      new Set<FunctionType>();
   
     /// Initially contains all classes that need RTI. After
     /// [computeNeededClasses]
  
positive.code:   }
  
    void registerDynamicFunctionTypeCheck(FunctionType functionType) {
      ClassElement classElement = Types.getClassContext(functionType);
      if (classElement != null) {
        checkedGenericFunctionTypes.putIfAbsent(classElement,
            () => new Set<FunctionType>()).add(functionType);
      } else {
        checkedNonGenericFunctionTypes.add(functionType);
      }
    }
  
    void emitRuntimeTypeSupport(CodeBuffer buffer, OutputUnit outputUnit) {
  
negative.code: part of dart2js.js_emitter;
  
  class TypeTestEmitter extends CodeEmitterHelper {
    /**
     * Raw ClassElement symbols occuring in is-checks and type assertions.  If the
     * program contains parameterized checks `x is Set<int>` and
  