Strong mode cleaning of many dart2js tests.

tests/compiler/dart2js/simple_inferrer_closure_test.dart

Index: tests/compiler/dart2js/simple_inferrer_closure_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_closure_test.dart b/tests/compiler/dart2js/simple_inferrer_closure_test.dart
index 39e581159fde20c468f079a28f5a901b740ac018..4899319120b07eb27f8cc3e4f3fa0e84bc72f6ce 100644
--- a/tests/compiler/dart2js/simple_inferrer_closure_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_closure_test.dart
@@ -146,7 +146,7 @@ void main() {
         checkReturn('returnNum1', closedWorld.commonMasks.numType);
 
         checkReturnInClass(String className, String methodName, type) {
-          var cls = findElement(compiler, className);
+          dynamic cls = findElement(compiler, className);
           var element = cls.lookupLocalMember(methodName);
           Expect.equals(
               type,
@@ -154,7 +154,7 @@ void main() {
                   typesInferrer.getReturnTypeOfElement(element), closedWorld));
         }
 
-        var cls = findElement(compiler, 'A');
+        dynamic cls = findElement(compiler, 'A');
         checkReturnInClass(
             'A', 'foo', new TypeMask.nonNullExact(cls, closedWorld));
       }));