Revert "Enqueue superclasses instead of supertypes."

pkg/compiler/lib/src/universe/universe.dart

Index: pkg/compiler/lib/src/universe/universe.dart
diff --git a/pkg/compiler/lib/src/universe/universe.dart b/pkg/compiler/lib/src/universe/universe.dart
index ccb402b878a67c3b4f26c3778d9958b5d1571676..e7d15beae169982cd403ce45ec303149f3e1505d 100644
--- a/pkg/compiler/lib/src/universe/universe.dart
+++ b/pkg/compiler/lib/src/universe/universe.dart
@@ -42,14 +42,6 @@ class UniverseSelector {
         (mask == null || mask.canHit(element, selector, world));
   }
 
-  int get hashCode => selector.hashCode * 13 + mask.hashCode * 17;
-
-  bool operator ==(other) {
-    if (identical(this, other)) return true;
-    if (other is! UniverseSelector) return false;
-    return selector == other.selector && mask == other.mask;
-  }
-
   String toString() => '$selector,$mask';
 }
 
@@ -159,9 +151,6 @@ class Universe {
   /// Invariant: Elements are declaration elements.
   final Set<ClassElement> _allInstantiatedClasses = new Set<ClassElement>();
 
-  /// Classes implemented by directly instantiated classes.
-  final Set<ClassElement> _implementedClasses = new Set<ClassElement>();
-
   /// The set of all referenced static fields.
   ///
   /// Invariant: Elements are declaration elements.
@@ -250,19 +239,12 @@ class Universe {
   Iterable<DartType> get instantiatedTypes => _instantiatedTypes;
 
   /// Returns `true` if [cls] is considered to be instantiated, either directly,
-  /// through subclasses.
+  /// through subclasses or through subtypes. The latter case only contains
+  /// spurious information from instatiations through factory constructors and
+  /// mixins.
   // TODO(johnniwinther): Improve semantic precision.
   bool isInstantiated(ClassElement cls) {
-    return _allInstantiatedClasses.contains(cls.declaration);
-  }
-
-  /// Returns `true` if [cls] is considered to be implemented by an
-  /// instantiated class, either directly, through subclasses or through
-  /// subtypes. The latter case only contains spurious information from
-  /// instantiations through factory constructors and mixins.
-  // TODO(johnniwinther): Improve semantic precision.
-  bool isImplemented(ClassElement cls) {
-    return _implementedClasses.contains(cls.declaration);
+    return _allInstantiatedClasses.contains(cls);
   }
 
   /// Register [type] as (directly) instantiated.
@@ -272,8 +254,7 @@ class Universe {
   // subclass and through subtype instantiated types/classes.
   // TODO(johnniwinther): Support unknown type arguments for generic types.
   void registerTypeInstantiation(InterfaceType type,
-                                 {bool byMirrors: false,
-                                  void onImplemented(ClassElement cls)}) {
+                                 {bool byMirrors: false}) {
     _instantiatedTypes.add(type);
     ClassElement cls = type.element;
     if (!cls.isAbstract
@@ -289,22 +270,11 @@ class Universe {
       _directlyInstantiatedClasses.add(cls);
     }
 
-    // TODO(johnniwinther): Replace this by separate more specific mappings that
-    // include the type arguments.
-    if (_implementedClasses.add(cls)) {
-      onImplemented(cls);
-      cls.allSupertypes.forEach((InterfaceType supertype) {
-        if (_implementedClasses.add(supertype.element)) {
-          onImplemented(supertype.element);
-        }
-      });
-    }
-    while (cls != null) {
-      if (!_allInstantiatedClasses.add(cls)) {
-        return;
-      }
-      cls = cls.superclass;
-    }
+    // TODO(johnniwinther): Replace this by separate more specific mappings.
+    if (!_allInstantiatedClasses.add(cls)) return;
+    cls.allSupertypes.forEach((InterfaceType supertype) {
+      _allInstantiatedClasses.add(supertype.element);
+    });
   }
 
   bool _hasMatchingSelector(Map<Selector, SelectorConstraints> selectors,