Add a test of summaries that uses strong mode.

pkg/analyzer/test/src/summary/summarize_elements_strong_test.dart

+// Copyright (c) 2016, 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.test.src.summary.summarize_elements_strong_test;
+
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:unittest/unittest.dart';
+
+import '../../reflective_tests.dart';
+import 'summarize_elements_test.dart';
+import 'summary_common.dart';
+
+main() {
+  groupSep = ' | ';
+  runReflectiveTests(SummarizeElementsStrongTest);
+}
+
+/**
+ * Override of [SummaryTest] which creates summaries from the element model
+ * using strong mode.
+ */
+@reflectiveTest
+class SummarizeElementsStrongTest extends SummarizeElementsTest {
+  @override
+  AnalysisOptionsImpl get options => super.options..strongMode = true;
+}