Revert "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 192513d27b98c1df79270130acb22a664f977a69..3fd8503e585d248dbc1a834d7ac3356571fde2c8 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
@@ -243,15 +243,7 @@ class SExpressionStringifier extends Indentation implements Visitor<String> {
   String visitTypeTest(TypeTest node) {
     String value = access(node.value);
     String typeArguments = node.typeArguments.map(access).join(' ');
-    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})';
+    return '(TypeTest $value ${node.dartType} ($typeArguments))';
   }
 
   String visitLiteralList(LiteralList node) {