boot.js: jQuery.allowJavaScriptCalls fix

js/boot.js

@@ -979,8 +979,8 @@ function MessageSendBrik(brikz, st) {
 		return st.send(st.JSObjectProxy._on_(receiver), selector, args);
 	}
 
-	if(this.jQuery) {
-		this.jQuery.allowJavaScriptCalls = true;
+	if(typeof jQuery !== "undefined") {
+		jQuery.allowJavaScriptCalls = true;
 	}
 
 	this.messageNotUnderstood = messageNotUnderstood;