Add ApplyChangesStatus to AnalysisContext.applyChanges() and use it in DAS.

pkg/analyzer/test/generated/engine_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 engine.engine_test;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/file_system/memory_file_system.dart';
@@ skipping 5844 matching lines @@
   void addListener(AnalysisListener listener) {
     fail("Unexpected invocation of addListener");
   }
 
   @override
   void applyAnalysisDelta(AnalysisDelta delta) {
     fail("Unexpected invocation of applyAnalysisDelta");
   }
 
   @override
-  void applyChanges(ChangeSet changeSet) {
+  ApplyChangesStatus applyChanges(ChangeSet changeSet) {
     fail("Unexpected invocation of applyChanges");
+    return null;
   }
 
   @override
   String computeDocumentationComment(Element element) {
     fail("Unexpected invocation of computeDocumentationComment");
     return null;
   }
 
   @override
   List<AnalysisError> computeErrors(Source source) {
@@ skipping 347 matching lines @@
   @override
   void visitContentCache(ContentCacheVisitor visitor) {
     fail("Unexpected invocation of visitContentCache");
   }
 }
 
 class TestAnalysisContext_test_applyChanges extends TestAnalysisContext {
   bool invoked = false;
   TestAnalysisContext_test_applyChanges();
   @override
-  void applyChanges(ChangeSet changeSet) {
+  ApplyChangesStatus applyChanges(ChangeSet changeSet) {
     invoked = true;
+    return new ApplyChangesStatus(false);
   }
 }
 
 class TestAnalysisContext_test_computeDocumentationComment
     extends TestAnalysisContext {
   bool invoked = false;
   TestAnalysisContext_test_computeDocumentationComment();
   @override
   String computeDocumentationComment(Element element) {
     invoked = true;
@@ skipping 801 matching lines @@
   @override
   bool exists() => true;
 }
 
 class _UniversalCachePartitionTest_test_setMaxCacheSize
     implements CacheRetentionPolicy {
   @override
   RetentionPriority getAstPriority(Source source, SourceEntry sourceEntry) =>
       RetentionPriority.LOW;
 }