Split TypedSelector into Selector and TypeMask.

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

Index: pkg/compiler/lib/src/types/forwarding_type_mask.dart
diff --git a/pkg/compiler/lib/src/types/forwarding_type_mask.dart b/pkg/compiler/lib/src/types/forwarding_type_mask.dart
index c57817a74c17bbb6f1211d3ceb48da4bcc4d8c93..ce29f506290fa1d4cf1797f8b3068ef707002bc4 100644
--- a/pkg/compiler/lib/src/types/forwarding_type_mask.dart
+++ b/pkg/compiler/lib/src/types/forwarding_type_mask.dart
@@ -96,8 +96,10 @@ abstract class ForwardingTypeMask implements TypeMask {
     return forwardTo.canHit(element, selector, classWorld);
   }
 
-  Element locateSingleElement(Selector selector, Compiler compiler) {
-    return forwardTo.locateSingleElement(selector, compiler);
+  Element locateSingleElement(Selector selector,
+                              TypeMask mask,
+                              Compiler compiler) {
+    return forwardTo.locateSingleElement(selector, mask, compiler);
   }
 
   bool equalsDisregardNull(other) {