Fix type masks for js-interop types.

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/backend_api.dart' show Backend;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'core_types.dart' show CoreClasses;
 import 'dart_types.dart';
 import 'elements/elements.dart'
     show
         ClassElement,
         Element,
         FunctionElement,
         MixinApplicationElement,
         TypedefElement,
         VariableElement;
+import 'js_backend/backend.dart' show JavaScriptBackend;
 import 'ordered_typeset.dart';
 import 'types/masks.dart' show TypeMask, FlatTypeMask;
 import 'universe/class_set.dart';
 import 'universe/function_set.dart' show FunctionSet;
 import 'universe/selector.dart' show Selector;
 import 'universe/side_effects.dart' show SideEffects;
 import 'util/util.dart' show Link;
 
 /// The [ClassWorld] represents the information known about a program when
 /// compiling with closed-world semantics.
@@ skipping 367 matching lines @@
     ClassSet classSet = _classSets[cls.declaration];
     if (classSet == null) {
       // Vacuously true.
       return true;
     }
     return classSet.hasOnlyInstantiatedSubclasses;
   }
 
   @override
   ClassElement getLubOfInstantiatedSubclasses(ClassElement cls) {
+    if (backend.isJsInterop(cls)) {
+      return backend.helpers.jsJavaScriptObjectClass;
+    }
     ClassHierarchyNode hierarchy = _classHierarchyNodes[cls.declaration];
     return hierarchy != null
         ? hierarchy.getLubOfInstantiatedSubclasses()
         : null;
   }
 
   @override
   ClassElement getLubOfInstantiatedSubtypes(ClassElement cls) {
+    if (backend.isJsInterop(cls)) {
+      return backend.helpers.jsJavaScriptObjectClass;
+    }
     ClassSet classSet = _classSets[cls.declaration];
     return classSet != null ? classSet.getLubOfInstantiatedSubtypes() : null;
   }
 
   /// Returns an iterable over the common supertypes of the [classes].
   Iterable<ClassElement> commonSupertypesOf(Iterable<ClassElement> classes) {
     Iterator<ClassElement> iterator = classes.iterator;
     if (!iterator.moveNext()) return const <ClassElement>[];
 
     ClassElement cls = iterator.current;
@@ skipping 115 matching lines @@
 
   /// Returns `true` if any subclass of [superclass] implements [type].
   bool hasAnySubclassThatImplements(
       ClassElement superclass, ClassElement type) {
     Set<ClassElement> subclasses = typesImplementedBySubclassesOf(superclass);
     if (subclasses == null) return false;
     return subclasses.contains(type);
   }
 
   final Compiler compiler;
-  Backend get backend => compiler.backend;
+  JavaScriptBackend get backend => compiler.backend;
   final FunctionSet allFunctions;
   final Set<Element> functionsCalledInLoop = new Set<Element>();
   final Map<Element, SideEffects> sideEffects = new Map<Element, SideEffects>();
 
   final Set<TypedefElement> allTypedefs = new Set<TypedefElement>();
 
   final Map<ClassElement, Set<MixinApplicationElement>> _mixinUses =
       new Map<ClassElement, Set<MixinApplicationElement>>();
   Map<ClassElement, List<MixinApplicationElement>> _liveMixinUses;
 
@@ skipping 311 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.options.hasIncrementalSupport;
 }