Issue 29360. Fix type name resolution for GenericTypeAliasElement.

pkg/analyzer/lib/src/dart/element/element.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.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 5218 matching lines @@
   }
 
   /**
    * Return the type of the function defined by this typedef after substituting
    * the given [typeArguments] for the type parameters defined for this typedef
    * (but not the type parameters defined by the function). If the number of
    * [typeArguments] does not match the number of type parameters, then
    * `dynamic` will be used in place of each of the type arguments.
    */
   FunctionType typeAfterSubstitution(List<DartType> typeArguments) {
+    GenericFunctionTypeElement function = this.function;
+    if (function == null) {
+      return null;
+    }
     FunctionType functionType = function.type;
     List<TypeParameterElement> parameterElements = typeParameters;
     List<DartType> parameterTypes =
         TypeParameterTypeImpl.getTypes(parameterElements);
     int parameterCount = parameterTypes.length;
     if (typeArguments == null ||
         parameterElements.length != typeArguments.length) {
       DartType dynamicType = DynamicElementImpl.instance.type;
       typeArguments = new List<DartType>.filled(parameterCount, dynamicType);
     }
@@ skipping 3847 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }