TAP5-2624: fixing broken test

org.apache.tapestry5.plastic.ProxyCreation > listen to plastic class
diff --git a/plastic/src/external/java/org/apache/tapestry5/internal/plastic/asm/util/TraceClassVisitor.java b/plastic/src/external/java/org/apache/tapestry5/internal/plastic/asm/util/TraceClassVisitor.java
index 1b2e706..f667957 100644
--- a/plastic/src/external/java/org/apache/tapestry5/internal/plastic/asm/util/TraceClassVisitor.java
+++ b/plastic/src/external/java/org/apache/tapestry5/internal/plastic/asm/util/TraceClassVisitor.java
@@ -119,7 +119,7 @@
    */
   public TraceClassVisitor(
       final ClassVisitor classVisitor, final Printer printer, final PrintWriter printWriter) {
-    super(/* latest api = */ Opcodes.ASM9_EXPERIMENTAL, classVisitor);
+    super(/* latest api = */ Opcodes.ASM8, classVisitor);
     this.printWriter = printWriter;
     this.p = printer;
   }