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

pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library simple_types_inferrer;
 
 import '../closure.dart' show
     ClosureClassMap,
     ClosureScope;
 import '../common.dart';
@@ skipping 629 matching lines @@
         // fields that we haven't initialized for sure.
         cls.forEachInstanceField((_, FieldElement field) {
           if (field.isFinal) return;
           T type = locals.fieldScope.readField(field);
           if (type == null && field.initializer == null) {
             inferrer.recordTypeOfNonFinalField(
                 spannable, field, types.nullType);
           }
         });
       }
-      if (analyzedElement.isGenerativeConstructor && cls.isAbstract) {
-        if (compiler.world.isDirectlyInstantiated(cls)) {
-          returnType = types.nonNullExact(cls);
-        } else if (compiler.world.isIndirectlyInstantiated(cls)) {
-          returnType = types.nonNullSubclass(cls);
-        } else  {
-          // TODO(johnniwinther): Avoid analyzing [analyzedElement] in this
-          // case; it's never called.
-          returnType = types.nonNullEmpty();
-        }
-      } else {
-        returnType = types.nonNullExact(cls);
-      }
+      returnType = types.nonNullExact(cls);
     } else {
       signature.forEachParameter((LocalParameterElement element) {
         locals.update(element, inferrer.typeOfElement(element), node);
       });
       visit(node.body);
       switch (function.asyncMarker) {
         case AsyncMarker.SYNC:
           if (returnType == null) {
             // No return in the body.
             returnType = locals.seenReturnOrThrow
@@ skipping 1668 matching lines @@
     TypeMask moveNextMask = elements.getMoveNextTypeMask(node);
 
     T iteratorType = handleDynamicSend(
         node, iteratorSelector, iteratorMask, expressionType,
         new ArgumentsTypes<T>.empty());
 
     return handleForInLoop(node, iteratorType, currentSelector, currentMask,
                            moveNextSelector, moveNextMask);
   }
 }