Tweaks to improve performance of type-inference.

pkg/compiler/lib/src/world.dart

 // Copyright (c) 2012, 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 dart2js.world;
 
 import 'closure.dart' show
     SynthesizedCallMethodElementX;
 import 'common.dart';
 import 'common/backend_api.dart' show
@@ skipping 292 matching lines @@
 
   /// Returns `true` if any directly instantiated class other than [cls]
   /// implements [cls].
   bool hasAnyStrictSubtype(ClassElement cls) {
     return !strictSubtypesOf(cls).isEmpty;
   }
 
   /// Returns `true` if all directly instantiated classes that implement [cls]
   /// extend it.
   bool hasOnlySubclasses(ClassElement cls) {
+    // TODO(johnniwinther): move this to ClassSet?
+    if (cls == objectClass) return true;
     Iterable<ClassElement> subtypes = strictSubtypesOf(cls);
     if (subtypes == null) return true;
     Iterable<ClassElement> subclasses = strictSubclassesOf(cls);
     return subclasses != null && (subclasses.length == subtypes.length);
   }
 
   @override
   ClassElement getLubOfInstantiatedSubclasses(ClassElement cls) {
     ClassHierarchyNode hierarchy = _classHierarchyNodes[cls.declaration];
     return hierarchy != null
@@ skipping 430 matching lines @@
     // function expressions's element.
     // TODO(herhut): Generate classes for function expressions earlier.
     if (element is SynthesizedCallMethodElementX) {
       return getMightBePassedToApply(element.expression);
     }
     return functionsThatMightBePassedToApply.contains(element);
   }
 
   bool get hasClosedWorldAssumption => !compiler.hasIncrementalSupport;
 }