Add a temporary analyzer error to work around #28515

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

 // Copyright (c) 2016, 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.declaration_resolver;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 368 matching lines @@
 
   @override
   Object visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
     super.visitTopLevelVariableDeclaration(node);
     _resolveMetadata(node, node.metadata, node.variables.variables[0].element);
     return null;
   }
 
   @override
   Object visitTypeParameter(TypeParameter node) {
+    if (node.parent.parent is FunctionTypedFormalParameter) {
+      // Work around dartbug.com/28515.
+      // TODO(paulberry): remove this once dartbug.com/28515 is fixed.
+      Element element = new TypeParameterElementImpl.forNode(node.name);
+      node.name?.staticElement = element;
+      return null;
+    }
     Element element = _match(node.name, _walker.getTypeParameter());
     super.visitTypeParameter(node);
     _resolveMetadata(node, node.metadata, element);
     return null;
   }
 
   @override
   Object visitVariableDeclaration(VariableDeclaration node) {
     VariableElement element = _match(node.name, _walker.getVariable());
     Expression initializer = node.initializer;
@@ skipping 316 matching lines @@
 class _ElementMismatchException extends AnalysisException {
   /**
    * Creates an exception to refer to the given [compilationUnit], [element],
    * and [cause].
    */
   _ElementMismatchException(
       CompilationUnitElement compilationUnit, Element element,
       [CaughtException cause = null])
       : super('Element mismatch in $compilationUnit at $element', cause);
 }