Extract SplatToArgsNode creation

* 377 -> 250 for org.truffleruby.language.dispatch.RubyCallNode.splatArgs
* subTreeCost 363 -> 237 in org.truffleruby.language.dispatch.RubyCallNode.execute

Author: eregon

src/main/java/org/truffleruby/language/dispatch/RubyCallNode.java

@@ -215,12 +215,16 @@ private void executeArguments(VirtualFrame frame, Object[] rubyArgs) {
     private Object[] splatArgs(Object receiverObject, Object[] rubyArgs) {
         if (splatToArgs == null) {
             CompilerDirectives.transferToInterpreterAndInvalidate();
-            splatToArgs = insert(new SplatToArgsNode(getLanguage()));
+            splatToArgs = createSplatToArgsNode();
         }
 
         return splatToArgs.execute(receiverObject, (RubyArray) RubyArguments.getArgument(rubyArgs, 0));
     }
 
+    private SplatToArgsNode createSplatToArgsNode() {
+        return insert(new SplatToArgsNode(getLanguage()));
+    }
+
     @Override
     public Object isDefined(VirtualFrame frame, RubyLanguage language, RubyContext context) {
         if (definedNode == null) {