Add stub versions of KernelInferrerEngine and friends

tests/compiler/dart2js/inference/inference_test_helper.dart

Index: tests/compiler/dart2js/inference/inference_test_helper.dart
diff --git a/tests/compiler/dart2js/inference/inference_test_helper.dart b/tests/compiler/dart2js/inference/inference_test_helper.dart
index 27e8323732ebb52a2bfe2957a7309fb0cffa4a7f..aa543c717405d7b2a6dbc415bf0d4dcb230214f0 100644
--- a/tests/compiler/dart2js/inference/inference_test_helper.dart
+++ b/tests/compiler/dart2js/inference/inference_test_helper.dart
@@ -42,12 +42,14 @@ class TypeMaskComputer extends AbstractResolvedAstComputer {
   String computeElementValue(AstElement element) {
     GlobalTypeInferenceElementResult elementResult;
     if (element.isParameter) {
-      elementResult = results.resultOfParameter(element);
+      ParameterElement parameter = element;
+      elementResult = results.resultOfParameter(parameter);
     } else if (element.isLocal) {
       LocalFunctionElement localFunction = element;
       elementResult = results.resultOfMember(localFunction.callMethod);
     } else {
-      elementResult = results.resultOfMember(element);
+      MemberElement member = element;
+      elementResult = results.resultOfMember(member);
     }
 
     TypeMask value =