[Truffle] Add an annotation for CoreMethod that only exist in Rubinius.

truffle/src/main/java/org/jruby/truffle/nodes/core/RegexpNodes.java

@@ -241,6 +241,7 @@ public Object match(RubyRegexp regexp, RubyString string) {
 
     }
 
+    @RubiniusOnly
     @CoreMethod(names = "match_start", required = 2)
     public abstract static class MatchStartNode extends CoreMethodNode {
 
@@ -323,6 +324,7 @@ public RubyString quote(RubySymbol raw) {
 
     }
 
+    @RubiniusOnly
     @CoreMethod(names = "search_from", required = 2)
     public abstract static class SearchFromNode extends CoreMethodNode {
 

truffle/src/main/java/org/jruby/truffle/nodes/core/RubiniusOnly.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2015 Oracle and/or its affiliates. All rights reserved. This
+ * code is released under a tri EPL/GPL/LGPL license. You can use it,
+ * redistribute it and/or modify it under the terms of the:
+ *
+ * Eclipse Public License version 1.0
+ * GNU General Public License version 2
+ * GNU Lesser General Public License version 2.1
+ */
+package org.jruby.truffle.nodes.core;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * A method that only exists in Rubinius but not in normal Ruby.
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.SOURCE)
+public @interface RubiniusOnly {
+}