Strong mode cleaning of many dart2js tests.

tests/compiler/dart2js/call_site_simple_type_inferer_test.dart

Index: tests/compiler/dart2js/call_site_simple_type_inferer_test.dart
diff --git a/tests/compiler/dart2js/call_site_simple_type_inferer_test.dart b/tests/compiler/dart2js/call_site_simple_type_inferer_test.dart
index 44ea2ba36dbf1d3142e5f7b7f8bcadc2f4856579..6759727c613b857d93a839d3624800ae5616497f 100644
--- a/tests/compiler/dart2js/call_site_simple_type_inferer_test.dart
+++ b/tests/compiler/dart2js/call_site_simple_type_inferer_test.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:async_helper/async_helper.dart';
+import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/types/masks.dart';
 import 'package:expect/expect.dart';
 
@@ -14,7 +15,7 @@ void compileAndFind(String code, String className, String memberName,
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(code, uri, disableInlining: disableInlining);
   asyncTest(() => compiler.run(uri).then((_) {
-        var cls = findElement(compiler, className);
+        ClassElement cls = findElement(compiler, className);
         var member = cls.lookupLocalMember(memberName);
         return check(compiler, member);
       }));