dart2js cps_ir: Use interceptors for is-checks (version 2)

pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
index 3fd8503e585d248dbc1a834d7ac3356571fde2c8..192513d27b98c1df79270130acb22a664f977a69 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
@@ -243,7 +243,15 @@ class SExpressionStringifier extends Indentation implements Visitor<String> {
   String visitTypeTest(TypeTest node) {
     String value = access(node.value);
     String typeArguments = node.typeArguments.map(access).join(' ');
-    return '(TypeTest $value ${node.dartType} ($typeArguments))';
+    String interceptor = node.interceptor == null
+        ? ''
+        : access(node.interceptor);
+    return '(TypeTest $value ${node.dartType} ($typeArguments) ($interceptor))';
+  }
+
+  String visitTypeTestViaFlag(TypeTestViaFlag node) {
+    String interceptor = access(node.interceptor);
+    return '(TypeTestViaFlag $interceptor ${node.dartType})';
   }
 
   String visitLiteralList(LiteralList node) {