roblox_emulator: isA alias for IsA

lib/roblox_emulator/src/runner/instance/instance.rs

@@ -206,12 +206,14 @@ impl mlua::UserData for Instance{
 				Ok(children)
 			})
 		);
-		methods.add_method("IsA",|lua,this,classname:mlua::String|
+		fn is_a(lua:&mlua::Lua,this:&Instance,classname:mlua::String)->mlua::Result<bool>{
 			dom_mut(lua,|dom|{
 				let instance=this.get(dom)?;
 				Ok(class_is_a(instance.class.as_str(),&*classname.to_str()?))
 			})
-		);
+		}
+		methods.add_method("isA",is_a);
+		methods.add_method("IsA",is_a);
 		methods.add_method("Destroy",|lua,this,()|
 			dom_mut(lua,|dom|{
 				dom.transfer_within(this.referent,Instance::nil().referent);