Delete global PHP object on shutdown

Deleting the global object implicitly deletes all the properties,
i.e. PHP objects we previously attached to it (and for which we
increased the reference counter).

Since the following idle notifications trigger the weak callbacks,
the references on the PHP objects are finally decreased.

v8js.cc

@@ -511,7 +511,18 @@ static void php_v8js_free_storage(void *object TSRMLS_DC) /* {{{ */
 	if (c->pending_exception) {
 		zval_ptr_dtor(&c->pending_exception);
 	}
-	
+
+	/* Delete PHP global object from JavaScript */
+	if (!c->context.IsEmpty()) {
+		v8::Locker locker(c->isolate);
+		v8::Isolate::Scope isolate_scope(c->isolate);
+		v8::HandleScope handle_scope(c->isolate);
+		v8::Context::Scope context_scope(c->isolate, c->context);
+
+		v8::Local<v8::String> object_name_js = v8::Local<v8::String>::New(c->isolate, c->object_name);
+		V8JS_GLOBAL->Delete(object_name_js);
+	}
+
 	c->object_name.Reset();
 	c->object_name.~Persistent();
 	c->global_template.Reset();