Delete a TODO task that has been taken care of.

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 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 221 matching lines @@
                 .singleWhere((PropertyAccessorElement e) => e.name == name),
             'getter $name');
       } else {
         comparePropertyAccessorElements(
             resynthesized.accessors[i],
             original.accessors
                 .singleWhere((PropertyAccessorElement e) => e.name == name),
             'setter $name');
       }
     }
-    // TODO(paulberry): test metadata and offsetToElementMap.
+    // Note: no need to test CompilationUnitElementImpl._offsetToElementMap
+    // since it is built on demand when needed (see
+    // CompilationUnitElementImpl.getElementAt])
   }
 
   void compareConstAstLists(
       List<Object> rItems, List<Object> oItems, String desc) {
     if (rItems == null && oItems == null) {
       return;
     }
     expect(rItems != null && oItems != null, isTrue);
     expect(rItems, hasLength(oItems.length));
     for (int i = 0; i < oItems.length; i++) {
@@ skipping 2742 matching lines @@
       fail('Unexpectedly tried to get unlinked summary for $uri');
     }
     return serializedUnit;
   }
 
   @override
   bool hasLibrarySummary(String uri) {
     return true;
   }
 }