Revert "Split TypedSelector into Selector and TypeMask."

pkg/compiler/lib/src/inferrer/inferrer_visitor.dart

Index: pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
diff --git a/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart b/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
index e8af9783dccabcb236a7a7f8aa2d0c2765e0eff2..3314fcdc308d712e688d8c76ee43aebfc308ae1f 100644
--- a/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
+++ b/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
@@ -47,7 +47,7 @@ abstract class TypeSystem<T> {
   T nonNullExact(ClassElement type);
   T nonNullEmpty();
   bool isNull(T type);
-  TypeMask newTypedSelector(T receiver, TypeMask mask);
+  Selector newTypedSelector(T receiver, Selector selector);
 
   T allocateList(T type,
                  Node node,
@@ -110,7 +110,7 @@ abstract class TypeSystem<T> {
    * Returns `true` if `selector` should be updated to reflect the new
    * `receiverType`.
    */
-  bool selectorNeedsUpdate(T receiverType, TypeMask mask);
+  bool selectorNeedsUpdate(T receiverType, Selector selector);
 
   /**
    * Returns a new receiver type for this [selector] applied to
@@ -120,10 +120,7 @@ abstract class TypeSystem<T> {
    * conditional send (e.g.  `a?.selector`), in which case the returned type may
    * be null.
    */
-  T refineReceiver(Selector selector,
-                   TypeMask mask,
-                   T receiverType,
-                   bool isConditional);
+  T refineReceiver(Selector selector, T receiverType, bool isConditional);
 
   /**
    * Returns the internal inferrer representation for [mask].