Stop defensively copying AST structures before resolution

pkg/analysis_server/test/analysis/notification_implemented_test.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 test.analysis.notification.implemented;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 19 matching lines @@
    * Validates that there is an [ImplementedClass] at the offset of [search].
    *
    * If [length] is not specified explicitly, then length of an identifier
    * from [search] is used.
    */
   void assertHasImplementedClass(String search, [int length = -1]) {
     int offset = findOffset(search);
     if (length == -1) {
       length = findIdentifierLength(search);
     }
+    if (implementedClasses == null) {
+      fail('No notification of impemented classes was received');
+    }
     for (ImplementedClass clazz in implementedClasses) {
       if (clazz.offset == offset && clazz.length == length) {
         return;
       }
     }
     fail('Expect to find an implemented class at $offset'
         ' in $implementedClasses');
   }
 
   /**
    * Validates that there is an [ImplementedClass] at the offset of [search].
    *
    * If [length] is not specified explicitly, then length of an identifier
    * from [search] is used.
    */
   void assertHasImplementedMember(String search, [int length = -1]) {
     int offset = findOffset(search);
     if (length == -1) {
       length = findIdentifierLength(search);
     }
+    if (implementedMembers == null) {
+      fail('No notification of impemented members was received');
+    }
     for (ImplementedMember member in implementedMembers) {
       if (member.offset == offset && member.length == length) {
         return;
       }
     }
     fail('Expect to find an implemented member at $offset'
         ' in $implementedMembers');
   }
 
   /**
    * Validates that there is no an [ImplementedClass] at the offset of [search].
    *
    * If [length] is not specified explicitly, then length of an identifier
    * from [search] is used.
    */
   void assertNoImplementedMember(String search, [int length = -1]) {
     int offset = findOffset(search);
     if (length == -1) {
       length = findIdentifierLength(search);
     }
+    if (implementedMembers == null) {
+      fail('No notification of impemented members was received');
+    }
     for (ImplementedMember member in implementedMembers) {
       if (member.offset == offset) {
         fail('Unexpected implemented member at $offset'
             ' in $implementedMembers');
       }
     }
   }
 
   @override
   Index createIndex() {
@@ skipping 220 matching lines @@
     Future waitForNotification(int times) {
       if (times == 0 || implementedClasses != null) {
         return new Future.value();
       }
       return new Future.delayed(
           new Duration(milliseconds:1), () => waitForNotification(times - 1));
     }
     return waitForNotification(30000);
   }
 }