Implement type argument access and reification of runtime types.

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 9d34f3d5ae82fd8b202c67117b9d1f3eef45f1e7..10aa6add1ac06b2cf565c2418fd057b66f6b254c 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
@@ -329,6 +329,14 @@ class SExpressionStringifier extends Indentation implements Visitor<String> {
   String visitInterceptor(Interceptor node) {
     return '(Interceptor ${access(node.input)})';
   }
+
+  String visitReifyRuntimeType(ReifyRuntimeType node) {
+    return '(ReifyRuntimeType ${access(node.value)})';
+  }
+
+  String visitReadTypeVariable(ReadTypeVariable node) {
+    return '(ReadTypeVariable ${access(node.target)}.${node.variable})';
+  }
 }
 
 class ConstantStringifier extends ConstantValueVisitor<String, Null> {