Fix for navigation reginos for instance creations with import prefixes.

pkg/analysis_server/test/analysis/notification_navigation_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.navigation;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/constants.dart';
@@ skipping 654 matching lines @@
     {
       assertHasRegionString('B<A>();', 'B'.length);
       assertHasTarget('B() {}', 0);
     }
     {
       assertHasRegion('A>();');
       assertHasTarget('A {');
     }
   }
 
+  test_instanceCreation_withImportPrefix_named() async {
+    addTestFile('''
+import 'dart:async' as ppp;
+main() {
+  new ppp.Future.value(42);
+}
+''');
+    await prepareNavigation();
+    {
+      assertHasRegion('ppp.');
+      assertHasTarget('ppp;');
+    }
+    assertHasRegion('Future.value');
+    assertHasRegion('value(42)');
+  }
+
   test_library() async {
     addTestFile('''
 library my.lib;
 ''');
     await prepareNavigation();
     assertHasRegionString('my.lib');
     assertHasTargetString('my.lib');
   }
 
   test_multiplyDefinedElement() async {
@@ skipping 226 matching lines @@
 
   test_type_void() async {
     addTestFile('''
 void main() {
 }
 ''');
     await prepareNavigation();
     assertNoRegionAt('void');
   }
 }