Remove dead code

common/space_lua/runtime.ts

@@ -529,18 +529,6 @@ export function luaGet(
   }
 }
 
-function isClass(obj: any) {
-  const isCtorClass = obj.constructor &&
-    obj.constructor.toString().substring(0, 5) === "class";
-  if (obj.prototype === undefined) {
-    return isCtorClass;
-  }
-  const isPrototypeCtorClass = obj.prototype.constructor &&
-    obj.prototype.constructor.toString &&
-    obj.prototype.constructor.toString().substring(0, 5) === "class";
-  return isCtorClass || isPrototypeCtorClass;
-}
-
 export function luaLen(obj: any): number {
   if (obj instanceof LuaTable) {
     return obj.length;