Reduce use of Element in optimize.dart

pkg/compiler/lib/src/types/type_mask.dart

Index: pkg/compiler/lib/src/types/type_mask.dart
diff --git a/pkg/compiler/lib/src/types/type_mask.dart b/pkg/compiler/lib/src/types/type_mask.dart
index e985433152937b3c35539f0074c9610cfa2accaa..bb4fcfd957eb8877c75303eec803f6a42365587d 100644
--- a/pkg/compiler/lib/src/types/type_mask.dart
+++ b/pkg/compiler/lib/src/types/type_mask.dart
@@ -349,7 +349,8 @@ abstract class TypeMask implements ReceiverConstraint, AbstractValue {
    * invoked on this type mask. [selector] is used to ensure library
    * privacy is taken into account.
    */
-  bool canHit(Element element, Selector selector, ClosedWorld closedWorld);
+  bool canHit(
+      MemberElement element, Selector selector, ClosedWorld closedWorld);
 
   /**
    * Returns the [element] that is known to always be hit at runtime