anchor.diff:  
   class InvocationInferenceHelper {
     final ResolverVisitor _resolver;
  -  final LibraryElementImpl _definingLibrary;
     final ElementTypeProvider _elementTypeProvider;
     final ErrorReporter _errorReporter;
     final FlowAnalysisHelper _flowAnalysis;
  
positive.code:     @required FlowAnalysisHelper flowAnalysis,
      @required TypeSystemImpl typeSystem,
    })  : _resolver = resolver,
          _definingLibrary = definingLibrary,
          _elementTypeProvider = elementTypeProvider,
          _errorReporter = errorReporter,
          _typeSystem = typeSystem,
  
negative.code: 
    /// Compute the return type of the method or function represented by the given
    /// type that is being invoked.
    DartType computeInvokeReturnType(DartType type,
        {@required bool isNullAware}) {
      TypeImpl returnType;
      if (type is FunctionType) {
        returnType = type.returnType ?? DynamicTypeImpl.instance;
      } else {
        returnType = DynamicTypeImpl.instance;
  