6921494: provide way to print javac tree tag values

Reviewed-by: jjg, mcimadamore
diff --git a/langtools/src/share/classes/com/sun/tools/javadoc/JavadocTool.java b/langtools/src/share/classes/com/sun/tools/javadoc/JavadocTool.java
index a5592ac..81bcdbd 100644
--- a/langtools/src/share/classes/com/sun/tools/javadoc/JavadocTool.java
+++ b/langtools/src/share/classes/com/sun/tools/javadoc/JavadocTool.java
@@ -419,7 +419,7 @@
         ListBuffer<JCClassDecl> result = new ListBuffer<JCClassDecl>();
         for (JCCompilationUnit t : trees) {
             for (JCTree def : t.defs) {
-                if (def.getTag() == JCTree.CLASSDEF)
+                if (def.hasTag(JCTree.Tag.CLASSDEF))
                     result.append((JCClassDecl)def);
             }
         }