fix #28519, assertion incorrectly triggering

pkg/analyzer/lib/src/generated/error_verifier.dart

 // Copyright (c) 2014, 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 analyzer.src.generated.error_verifier;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 3981 matching lines @@
   }
 
   void _checkForImplicitDynamicInvoke(InvocationExpression node) {
     if (_options.implicitDynamic ||
         node == null ||
         node.typeArguments != null) {
       return;
     }
     DartType invokeType = node.staticInvokeType;
     DartType declaredType = node.function.staticType;
-    if (invokeType is FunctionType && declaredType is FunctionType) {
+    if (invokeType is FunctionType &&
+        declaredType is FunctionType &&
+        declaredType.typeFormals.isNotEmpty) {
       Iterable<DartType> typeArgs =
           FunctionTypeImpl.recoverTypeArguments(declaredType, invokeType);
       if (typeArgs.any((t) => t.isDynamic)) {
         // Issue an error depending on what we're trying to call.
         Expression function = node.function;
         if (function is Identifier) {
           Element element = function.staticElement;
           if (element is MethodElement) {
             _errorReporter.reportErrorForNode(
                 StrongModeCode.IMPLICIT_DYNAMIC_METHOD,
@@ skipping 3050 matching lines @@
 class _InvocationCollector extends RecursiveAstVisitor {
   final List<String> superCalls = <String>[];
 
   @override
   visitMethodInvocation(MethodInvocation node) {
     if (node.target is SuperExpression) {
       superCalls.add(node.methodName.name);
     }
   }
 }