Fix for creating the correct SdkAnalysisContext.

pkg/analyzer/lib/src/generated/sdk_io.dart

Index: pkg/analyzer/lib/src/generated/sdk_io.dart
diff --git a/pkg/analyzer/lib/src/generated/sdk_io.dart b/pkg/analyzer/lib/src/generated/sdk_io.dart
index cd9c959529ea296f5b208401f6bc67d21db14e6d..21dff72cd50cd292515288a5e789ffe8ab00f303 100644
--- a/pkg/analyzer/lib/src/generated/sdk_io.dart
+++ b/pkg/analyzer/lib/src/generated/sdk_io.dart
@@ -9,6 +9,7 @@ library engine.sdk.io;
 
 import 'dart:io';
 
+import 'package:analyzer/src/context/context.dart' as newContext;
 import 'package:analyzer/src/generated/java_engine.dart';
 
 import 'ast.dart';
@@ -232,7 +233,11 @@ class DirectoryBasedDartSdk implements DartSdk {
   @override
   AnalysisContext get context {
     if (_analysisContext == null) {
-      _analysisContext = new SdkAnalysisContext();
+      if (AnalysisEngine.instance.useTaskModel) {
+        _analysisContext = new newContext.SdkAnalysisContext();
+      } else {
+        _analysisContext = new SdkAnalysisContext();
+      }
       SourceFactory factory = new SourceFactory([new DartUriResolver(this)]);
       _analysisContext.sourceFactory = factory;
       List<String> uris = this.uris;