Split TypedSelector into Selector and TypeMask.

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

Index: pkg/compiler/lib/src/types/flat_type_mask.dart
diff --git a/pkg/compiler/lib/src/types/flat_type_mask.dart b/pkg/compiler/lib/src/types/flat_type_mask.dart
index 2fa32efb6fce006ae09cc573d902fe31a2d04181..545fe7ccdd962e336e1c0ac9715a8a7030abdddf 100644
--- a/pkg/compiler/lib/src/types/flat_type_mask.dart
+++ b/pkg/compiler/lib/src/types/flat_type_mask.dart
@@ -634,9 +634,12 @@ class FlatTypeMask implements TypeMask {
            subclassesToCheck.any(needsNoSuchMethod);
   }
 
-  Element locateSingleElement(Selector selector, Compiler compiler) {
+  Element locateSingleElement(Selector selector,
+                              TypeMask mask,
+                              Compiler compiler) {
     if (isEmpty) return null;
-    Iterable<Element> targets = compiler.world.allFunctions.filter(selector);
+    Iterable<Element> targets =
+        compiler.world.allFunctions.filter(selector, mask);
     if (targets.length != 1) return null;
     Element result = targets.first;
     ClassElement enclosing = result.enclosingClass;