"use strict"; test(() => { const observableArray = document.adoptedStyleSheets; let leaked_target = null; let leaked_handler = null; let target_leaker = (target) => { leaked_target = target; return null; }; Object.defineProperty(Object.prototype, "getPrototypeOf", {get: function() { leaked_handler = this; return target_leaker; }}) Object.getPrototypeOf(observableArray); assert_equals(leaked_target, null, "The proxy target leaked."); assert_equals(leaked_handler, null, "The proxy handler leaked."); }, "ObservableArray's internals won't leak");