Prepare for decoupling analyzer ASTs from element model.

pkg/analyzer/lib/src/context/context.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 analyzer.src.context.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/resolution_accessors.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/exception/exception.dart';
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer/plugin/resolver_provider.dart';
 import 'package:analyzer/plugin/task.dart';
 import 'package:analyzer/src/cancelable_future.dart';
 import 'package:analyzer/src/context/builder.dart' show EmbedderYamlLocator;
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/dart/element/element.dart';
@@ skipping 1916 matching lines @@
       bool success = resolver.resolve(newCode);
       AnalysisEngine.instance.instrumentationService.logPerformance(
           AnalysisPerformanceKind.INCREMENTAL,
           perfCounter,
           'success=$success,context_id=$_id,code_length=${newCode.length}');
       if (!success) {
         return false;
       }
       // if validation, remember the result, but throw it away
       if (analysisOptions.incrementalValidation) {
-        incrementalResolutionValidation_lastUnitSource = oldUnit.element.source;
+        CompilationUnitElement compilationUnitElement =
+            elementForCompilationUnit(oldUnit);
+        incrementalResolutionValidation_lastUnitSource =
+            compilationUnitElement.source;
         incrementalResolutionValidation_lastLibrarySource =
-            oldUnit.element.library.source;
+            compilationUnitElement.library.source;
         incrementalResolutionValidation_lastUnit = oldUnit;
         return false;
       }
       // prepare notice
       {
         ChangeNoticeImpl notice = getNotice(unitSource);
         notice.resolvedDartUnit = oldUnit;
         AnalysisErrorInfo errorInfo = getErrors(unitSource);
         notice.setErrors(errorInfo.errors, errorInfo.lineInfo);
       }
@@ skipping 284 matching lines @@
     }
     DartSdk sdk = factory.dartSdk;
     if (sdk == null) {
       throw new ArgumentError(
           "The source factory for an SDK analysis context must have a DartUriResolver");
     }
     return new AnalysisCache(
         <CachePartition>[AnalysisEngine.instance.partitionManager.forSdk(sdk)]);
   }
 }