Fix dead code hints in summary code.

pkg/analyzer/lib/src/summary/summarize_elements.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 serialization.elements;
 
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:analyzer/src/summary/builder.dart';
@@ skipping 522 matching lines @@
     }
     return b;
   }
 
   /**
    * Serialize the given [type] into an [UnlinkedTypeRef].
    */
   UnlinkedTypeRefBuilder serializeTypeRef(DartType type, Element context) {
     UnlinkedTypeRefBuilder b = new UnlinkedTypeRefBuilder(ctx);
     if (type is TypeParameterType) {
-      Element enclosingElement = type.element.enclosingElement;
       b.paramReference = findTypeParameterIndex(type, context);
     } else {
       Element element = type.element;
-      CompilationUnitElement dependentCompilationUnit =
-          element.getAncestor((Element e) => e is CompilationUnitElement);
       LibraryElement dependentLibrary = element.library;
       if (dependentLibrary == null) {
         assert(type.isDynamic);
         if (type is UndefinedTypeImpl) {
           b.reference = serializeUnresolvedReference();
         } else {
           b.reference = serializeDynamicReference();
         }
       } else {
         b.reference = referenceMap.putIfAbsent(element, () {
@@ skipping 65 matching lines @@
     b.name = variable.name;
     b.unit = unitNum;
     b.type = serializeTypeRef(variable.type, variable);
     b.isStatic = variable.isStatic && variable.enclosingElement is ClassElement;
     b.isFinal = variable.isFinal;
     b.isConst = variable.isConst;
     b.hasImplicitType = variable.hasImplicitType;
     return b;
   }
 }