dart2js cps: 'is' checks on types with type arguments.

pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.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 dart2js.ir_builder_task;
 
 import '../closure.dart' as closurelib;
 import '../closure.dart' hide ClosureScope;
 import '../constants/expressions.dart';
 import '../dart_types.dart';
@@ skipping 859 matching lines @@
     ir.Primitive receiver = visit(expression);
     return irBuilder.buildTypeOperator(receiver, type, isTypeTest: false);
   }
 
   @override
   ir.Primitive visitIs(
       ast.Send node,
       ast.Node expression,
       DartType type,
       _) {
-    ir.Primitive receiver = visit(expression);
-    return irBuilder.buildTypeOperator(
-        receiver, type,
-        isTypeTest: true,
-        isNotCheck: false);
+    ir.Primitive value = visit(expression);
+    return irBuilder.buildTypeOperator(value, type, isTypeTest: true);
   }
 
   @override
   ir.Primitive visitIsNot(ast.Send node,
                           ast.Node expression, DartType type, _) {
-    ir.Primitive receiver = visit(expression);
-    return irBuilder.buildTypeOperator(
-        receiver, type,
-        isTypeTest: true,
-        isNotCheck: true);
+    ir.Primitive value = visit(expression);
+    ir.Primitive check = irBuilder.buildTypeOperator(
+        value, type, isTypeTest: true);
+    return irBuilder.buildNegation(check);
   }
 
   ir.Primitive translateBinary(ast.Node left,
                                op.BinaryOperator operator,
                                ast.Node right) {
     Selector selector = new Selector.binaryOperator(operator.selectorName);
     ir.Primitive receiver = visit(left);
     List<ir.Primitive> arguments = <ir.Primitive>[visit(right)];
     arguments = normalizeDynamicArguments(selector.callStructure, arguments);
     return irBuilder.buildDynamicInvocation(receiver, selector, arguments);
@@ skipping 1395 matching lines @@
   JavaScriptBackend get _backend => _compiler.backend;
 
   GlobalProgramInformation(this._compiler);
 
   /// Returns [true], if the analysis could not determine that the type
   /// arguments for the class [cls] are never used in the program.
   bool requiresRuntimeTypesFor(ClassElement cls) {
     return cls.typeVariables.isNotEmpty && _backend.classNeedsRti(cls);
   }
 
-  Set<ClassElement> get interceptedClasses => _backend.interceptedClasses;
+  ClassElement get nullClass => _compiler.nullClass;
 }
 
 /// IR builder specific to the JavaScript backend, coupled to the [JsIrBuilder].
 class JsIrBuilderVisitor extends IrBuilderVisitor {
   /// Promote the type of [irBuilder] to [JsIrBuilder].
   JsIrBuilder get irBuilder => super.irBuilder;
 
   JavaScriptBackend get backend => compiler.backend;
 
   /// Result of closure conversion for the current body of code.
@@ skipping 758 matching lines @@
     node.body = replacementFor(node.body);
   }
 }
 
 /// Visit a just-deleted subterm and unlink all [Reference]s in it.
 class RemovalVisitor extends ir.RecursiveVisitor {
   processReference(ir.Reference reference) {
     reference.unlink();
   }
 }