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

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

Index: pkg/compiler/lib/src/js_backend/codegen/codegen.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
index c133788a1f9a2fa81d5a5ebb791b7f7702173bc7..0a2242477998b51f0e5c8b0db4dc789a28998829 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
@@ -350,40 +350,14 @@ class CodeGenerator extends tree_ir.StatementVisitor
 
   @override
   js.Expression visitTypeOperator(tree_ir.TypeOperator node) {
-    js.Expression value = visitExpression(node.value);
-    List<js.Expression> typeArguments =
-        node.typeArguments.map(visitExpression).toList();
     if (!node.isTypeTest) {
       giveup(node, 'type casts not implemented.');
     }
     DartType type = node.type;
-    // Note that the trivial (but special) cases of Object, dynamic, and Null
-    // are handled at build-time and must not occur in a TypeOperator.
-    assert(!type.isObject && !type.isDynamic);
-    if (type is InterfaceType) {
+    if (type is InterfaceType && type.isRaw) {
       glue.registerIsCheck(type, registry);
-      ClassElement clazz = type.element;
-
-      // We use the helper:
-      //
-      //     checkSubtype(value, $isT, typeArgs, $asT)
-      //
-      // Any of the last two arguments may be null if there are no type
-      // arguments, and/or if no substitution is required.
-
-      js.Expression isT = js.string(glue.getTypeTestTag(type));
-
-      js.Expression typeArgumentArray = typeArguments.isNotEmpty
-          ? new js.ArrayInitializer(typeArguments)
-          : new js.LiteralNull();
-
-      js.Expression asT = glue.hasStrictSubtype(clazz)
-          ? js.string(glue.getTypeSubstitutionTag(clazz))
-          : new js.LiteralNull();
-
-      return buildStaticHelperInvocation(
-          glue.getCheckSubtype(),
-          [value, isT, typeArgumentArray, asT]);
+      js.Expression value = visitExpression(node.receiver);
+      return js.js('!!#.#', [value, glue.getTypeTestTag(type)]);
     }
     return giveup(node, 'type check unimplemented for $type.');
   }