Address Peter's comments in https://codereview.chromium.org/11361059, and fix a host-checked mode b…

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

Index: sdk/lib/_internal/compiler/implementation/universe/universe.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/universe/universe.dart	(revision 14518)
+++ sdk/lib/_internal/compiler/implementation/universe/universe.dart	(working copy)
@@ -422,7 +422,12 @@
       return appliesUntyped(element, compiler);
     }
 
-    ClassElement self = receiverType.element;
+    Element self = receiverType.element;
+    if (self.isTypedef()) {
+      // A typedef is a function type that doesn't have any
+      // user-defined members.
+      return false;
+    }
 
     if (other.implementsInterface(self)
         || other.isSubclassOf(self)
@@ -430,7 +435,9 @@
       return appliesUntyped(element, compiler);
     }
 
-    if (!self.isTypedef() && !self.isInterface() && self.isSubclassOf(other)) {
+    // If [self] is a subclass of [other], it inherits the
+    // implementation of [element].
+    if (self.isSubclassOf(other)) {
       // Resolve an invocation of [element.name] on [self]. If it
       // is found, this selector is a candidate.
       return hasElementIn(self, element) && appliesUntyped(element, compiler);