fix #25794, infer parameter type from default value, in AST summaries

pkg/analyzer/test/src/summary/resynthesize_ast_test.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.test.src.summary.resynthesize_ast_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart'
@@ skipping 492 matching lines @@
   }
 
   @override
   @failingTest
   void test_inferCorrectlyOnMultipleVariablesDeclaredTogether() {
     super.test_inferCorrectlyOnMultipleVariablesDeclaredTogether();
   }
 
   @override
   @failingTest
-  void test_inferDefaultFormalParameter() {
-    super.test_inferDefaultFormalParameter();
-  }
-
-  @override
-  @failingTest
   void test_inferenceInCyclesIsDeterministic() {
     super.test_inferenceInCyclesIsDeterministic();
   }
 
   @override
   @failingTest
   void test_inferredType_opAssignToProperty_prefixedIdentifier() {
     super.test_inferredType_opAssignToProperty_prefixedIdentifier();
   }
 
@@ skipping 172 matching lines @@
     }
 
     UnlinkedUnit definingUnit = _getUnlinkedUnit(librarySource);
     LinkedLibraryBuilder linkedLibrary =
         prelink(definingUnit, getPart, getImport);
     linkedLibrary.dependencies.skip(1).forEach((LinkedDependency d) {
       _serializeLibrary(resolveRelativeUri(d.uri));
     });
   }
 }