Properly resynthesize field formal parameter elements.

pkg/analyzer/test/src/summary/resynthesize_test.dart

 // Copyright (c) 2015, 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 test.src.serialization.elements_test;
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
@@ skipping 336 matching lines @@
       ParameterElementImpl original, String desc) {
     compareVariableElements(resynthesized, original, desc);
     expect(resynthesized.parameters.length, original.parameters.length);
     for (int i = 0; i < resynthesized.parameters.length; i++) {
       compareParameterElements(
           resynthesized.parameters[i],
           original.parameters[i],
           '$desc parameter ${original.parameters[i].name}');
     }
     expect(resynthesized.parameterKind, original.parameterKind);
+    expect(resynthesized.isInitializingFormal, original.isInitializingFormal,
+        reason: desc);
+    expect(resynthesized is FieldFormalParameterElementImpl,
+        original is FieldFormalParameterElementImpl);
+    if (resynthesized is FieldFormalParameterElementImpl &&
+        original is FieldFormalParameterElementImpl) {
+      if (original.field == null) {
+        expect(resynthesized.field, isNull, reason: '$desc field');
+      } else {
+        expect(resynthesized.field, isNotNull, reason: '$desc field');
+        compareFieldElements(
+            resynthesized.field, original.field, '$desc field');
+      }
+    }
   }
 
   void comparePrefixElements(PrefixElementImpl resynthesized,
       PrefixElementImpl original, String desc) {
     compareElements(resynthesized, original, desc);
     // TODO(paulberry): test _importedLibraries.
   }
 
   void comparePropertyAccessorElements(
       PropertyAccessorElementImpl resynthesized,
@@ skipping 1247 matching lines @@
       fail('Unexpectedly tried to get unlinked summary for $uri');
     }
     return serializedUnit;
   }
 
   @override
   bool hasLibrarySummary(String uri) {
     return true;
   }
 }