Use JRuby's built-in JSR-223 implementation

We had our own, but it is no longer necessary, because JRuby now
provides its own, which will assuredly be better maintained than ours.

This avoids and fixes many problems with JRuby scripting support.

Author: ctrueden

src/main/java/org/scijava/plugins/scripting/jruby/JRubyBindings.java

@@ -40,7 +40,7 @@
 /**
  * An adapter of the JRuby interpreter to the SciJava scripting interface.
  * 
- * @author Johannes Schindelin
+ * @author Curtis Rueden
  * @see ScriptEngine
  */
 @Plugin(type = ScriptLanguage.class, name = "Ruby")
@@ -50,10 +50,4 @@ public JRubyScriptLanguage() {
 		super("jruby");
 	}
 
-	@Override
-	public ScriptEngine getScriptEngine() {
-		// TODO: Consider adapting the wrapped ScriptEngineFactory's ScriptEngine.
-		return new JRubyScriptEngine();
-	}
-
 }

src/main/java/org/scijava/plugins/scripting/jruby/JRubyScriptEngine.java

@@ -43,7 +43,6 @@
 
 import org.junit.Test;
 import org.scijava.Context;
-import org.scijava.plugins.scripting.jruby.JRubyScriptEngine;
 import org.scijava.script.ScriptLanguage;
 import org.scijava.script.ScriptModule;
 import org.scijava.script.ScriptService;
@@ -63,10 +62,8 @@ public void testBasic() throws InterruptedException, ExecutionException,
 		final ScriptService scriptService = context.getService(ScriptService.class);
 		final String script = "$x = 1 + 2;";
 		final ScriptModule m = scriptService.run("add.rb", script, true).get();
-		final ScriptEngine engine = (ScriptEngine) m.getReturnValue();
-		final Object result = engine.get("$x");
-		// NB: Result is of type org.jruby.RubyFixnum.
-		assertEquals("3", result.toString());
+		final Object result = m.getReturnValue();
+		assertEquals(3L, result);
 	}
 
 	@Test
@@ -76,14 +73,15 @@ public void testLocals() throws ScriptException {
 
 		final ScriptLanguage language = scriptService.getLanguageByExtension("rb");
 		final ScriptEngine engine = language.getScriptEngine();
-		assertEquals(JRubyScriptEngine.class, engine.getClass());
-		engine.put("$hello", 17);
-		assertEquals("17", engine.eval("$hello").toString());
-		assertEquals("17", engine.get("$hello").toString());
+		final String engineClassName = engine.getClass().getName();
+		assertEquals("org.jruby.embed.jsr223.JRubyEngine", engineClassName);
+		engine.put("hello", 17);
+		assertEquals("17", engine.eval("hello").toString());
+		assertEquals("17", engine.get("hello").toString());
 
 		final Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);
 		bindings.clear();
-		assertEquals("", engine.get("$hello").toString());
+		assertEquals("", engine.get("hello").toString());
 	}
 
 	// FIXME: This test currently fails due to input injection failure.