Revert "Normalize type masks to use the least upper instantiated subclass/type."

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 c8e39a43242f6954403302d51f42ddbef6938466..5f9fd4632487d19bd496ee8ea7d03e65a56f5380 100644
--- a/pkg/compiler/lib/src/universe/universe.dart
+++ b/pkg/compiler/lib/src/universe/universe.dart
@@ -124,6 +124,12 @@ class Universe {
   /// See [_directlyInstantiatedClasses].
   final Set<DartType> _instantiatedTypes = new Set<DartType>();
 
+  /// The set of all instantiated classes, either directly, as superclasses or
+  /// as supertypes.
+  ///
+  /// 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>();
 
@@ -200,6 +206,13 @@ class Universe {
     return _directlyInstantiatedClasses;
   }
 
+  /// All instantiated classes, either directly, as superclasses or as
+  /// supertypes.
+  // TODO(johnniwinther): Improve semantic precision.
+  Iterable<ClassElement> get allInstantiatedClasses {
+    return _allInstantiatedClasses;
+  }
+
   /// All directly instantiated types, that is, the types of the directly
   /// instantiated classes.
   ///
@@ -207,6 +220,13 @@ class Universe {
   // TODO(johnniwinther): Improve semantic precision.
   Iterable<DartType> get instantiatedTypes => _instantiatedTypes;
 
+  /// Returns `true` if [cls] is considered to be instantiated, either directly,
+  /// through subclasses.
+  // 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
@@ -251,6 +271,12 @@ class Universe {
         }
       });
     }
+    while (cls != null) {
+      if (!_allInstantiatedClasses.add(cls)) {
+        return;
+      }
+      cls = cls.superclass;
+    }
   }
 
   bool _hasMatchingSelector(Map<Selector, SelectorConstraints> selectors,
@@ -377,6 +403,7 @@ class Universe {
     fieldSetters.remove(element);
     fieldGetters.remove(element);
     _directlyInstantiatedClasses.remove(element);
+    _allInstantiatedClasses.remove(element);
     if (element is ClassElement) {
       assert(invariant(
           element, element.thisType.isRaw,