Fix type masks for js-interop types.

pkg/compiler/lib/src/js_backend/no_such_method_registry.dart

 // Copyright (c) 2015, 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.
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers, Names, Selectors;
 import '../compiler.dart' show Compiler;
 import '../elements/elements.dart';
 import '../tree/tree.dart';
 import '../types/types.dart';
@@ skipping 132 matching lines @@
     if (otherImpls.contains(element)) {
       return NsmCategory.OTHER;
     }
     if (notApplicableImpls.contains(element)) {
       return NsmCategory.NOT_APPLICABLE;
     }
     if (!Selectors.noSuchMethod_.signatureApplies(element)) {
       notApplicableImpls.add(element);
       return NsmCategory.NOT_APPLICABLE;
     }
-    if (_isDefaultNoSuchMethodImplementation(element)) {
+    if (isDefaultNoSuchMethodImplementation(element)) {
       defaultImpls.add(element);
       return NsmCategory.DEFAULT;
     } else if (_hasForwardingSyntax(element)) {
       // If the implementation is 'noSuchMethod(x) => super.noSuchMethod(x);'
       // then it is in the same category as the super call.
       Element superCall =
           element.enclosingClass.lookupSuperByName(Names.noSuchMethod_);
       NsmCategory category = _categorizeImpl(superCall);
       switch (category) {
         case NsmCategory.DEFAULT:
@@ skipping 15 matching lines @@
       return category;
     } else if (_hasThrowingSyntax(element)) {
       throwingImpls.add(element);
       return NsmCategory.THROWING;
     } else {
       otherImpls.add(element);
       return NsmCategory.OTHER;
     }
   }
 
-  bool _isDefaultNoSuchMethodImplementation(FunctionElement element) {
+  bool isDefaultNoSuchMethodImplementation(FunctionElement element) {
     ClassElement classElement = element.enclosingClass;
     return classElement == _compiler.coreClasses.objectClass ||
         classElement == _backend.helpers.jsInterceptorClass ||
         classElement == _backend.helpers.jsNullClass;
   }
 
   bool _hasForwardingSyntax(FunctionElement element) {
     // At this point we know that this is signature-compatible with
     // Object.noSuchMethod, but it may have more than one argument as long as
     // it only has one required argument.
@@ skipping 62 matching lines @@
       if (body.statements.nodes.head is ExpressionStatement) {
         ExpressionStatement stmt = body.statements.nodes.head;
         return stmt.expression is Throw;
       }
     }
     return false;
   }
 }
 
 enum NsmCategory { DEFAULT, THROWING, NOT_APPLICABLE, OTHER, }