Handle instance fields in compile_from_dill_test

pkg/compiler/lib/src/elements/common.dart

Index: pkg/compiler/lib/src/elements/common.dart
diff --git a/pkg/compiler/lib/src/elements/common.dart b/pkg/compiler/lib/src/elements/common.dart
index 003efbb3e8739f485dc7834bd13a45d8d2dcfc97..42fbeccacab3b72a06ce280a53913e7d4cf85a20 100644
--- a/pkg/compiler/lib/src/elements/common.dart
+++ b/pkg/compiler/lib/src/elements/common.dart
@@ -414,7 +414,7 @@ abstract class ClassElementCommon implements ClassElement {
    * This method also works if the [fieldMember] is private.
    */
   @override
-  bool hasFieldShadowedBy(Element fieldMember) {
+  bool hasFieldShadowedBy(FieldElement fieldMember) {
     assert(fieldMember.isField);
     String fieldName = fieldMember.name;
     bool isPrivate = Name.isPrivateName(fieldName);