Teach Selector.applies about mixins.

sdk/lib/_internal/compiler/implementation/universe/universe.dart

Index: sdk/lib/_internal/compiler/implementation/universe/universe.dart
diff --git a/sdk/lib/_internal/compiler/implementation/universe/universe.dart b/sdk/lib/_internal/compiler/implementation/universe/universe.dart
index be9a0e506c51f4c6c800a2de8957dc5f3feefada..4fb6cfbbf7c2bfa66af96980fda3010bdc4eb82e 100644
--- a/sdk/lib/_internal/compiler/implementation/universe/universe.dart
+++ b/sdk/lib/_internal/compiler/implementation/universe/universe.dart
@@ -515,12 +515,15 @@ class TypedSelector extends Selector {
     if (typeKind == TypedSelectorKind.EXACT) {
       return hasElementIn(self, element) && appliesUntyped(element, compiler);
     } else if (typeKind == TypedSelectorKind.SUBCLASS) {
-      return (hasElementIn(self, element) || other.isSubclassOf(self))
+      return (hasElementIn(self, element)
+              || other.isSubclassOf(self)
+              || compiler.world.hasAnySubclassThatMixes(self, other))
           && appliesUntyped(element, compiler);
     } else {
       assert(typeKind == TypedSelectorKind.INTERFACE);
       if (other.implementsInterface(self)
           || other.isSubclassOf(self)
+          || compiler.world.hasAnySubclassThatMixes(self, other)
           || compiler.world.hasAnySubclassThatImplements(other, receiverType)) {
         return appliesUntyped(element, compiler);
       }