Fixed String.fromCharCode when using reflection

[NeeEoo]

Fixes #1103

Sorry if the code is bad, i don't know the proper way to do this. Feel free to edit this pr.

try {
    Reflect.callMethod(null, Reflect.field(String, "fromCharCode"), [65]);
    Sys.println("String.fromCharCode works from reflect.");
} catch(e:Dynamic) {
    Sys.println("[ERROR] String.fromCharCode doesn't work from reflect.");
}

[MAJigsaw77]

Any progress on merging this?