Removed LockerService Restriction on instanceof in JavaScript

Previously, we advised against using the instanceof operator in JavaScript code when LockerService is activated. This restriction has been removed, except when checking arrays.

Except when checking arrays, feel free to use instanceof in your components or upload static resources for third-party libraries that use instanceof in their internals.

To check if a given object is an array, use Array.isArray(objToTest) instead of instanceof. LockerService uses the standard JavaScript Proxy object. Proxy doesn’t support using instanceof with a native array.