Issue 27392. Fix for invoking objects with function-bounds type parameter types.

pkg/analyzer/lib/src/generated/element_resolver.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.element_resolver;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/syntactic_entity.dart';
@@ skipping 1601 matching lines @@
       }
     }
     return false;
   }
 
   /**
    * Return `true` if the given [type] represents an object that could be
    * invoked using the call operator '()'.
    */
   bool _isExecutableType(DartType type) {
+    type = type?.resolveToBound(_resolver.typeProvider.objectType);
     if (type.isDynamic || type is FunctionType) {
       return true;
     } else if (!_enableStrictCallChecks &&
         (type.isDartCoreFunction || type.isObject)) {
       return true;
     } else if (type is InterfaceType) {
       ClassElement classElement = type.element;
       // 16078 from Gilad: If the type is a Functor with the @proxy annotation,
       // treat it as an executable type.
       // example code: NonErrorResolverTest.
@@ skipping 1005 matching lines @@
 
   @override
   Element get staticElement => null;
 
   @override
   dynamic/*=E*/ accept/*<E>*/(AstVisitor/*<E>*/ visitor) => null;
 
   @override
   void visitChildren(AstVisitor visitor) {}
 }