I am looking into ways to extend Firefox pop-up blocking from an extension. One option is replacing window.open() (or rather Window.prototype.open()) in the webpage by a wrapper function. An important requirement is that this manipulation cannot be detected or reverted by the webpage. For example, if I simply do this:
Window.prototype.open = wrapper;
The webpage can easily revert the change by doing:
delete Window.prototype.open;
Instead I can use Object.defineProperty() to set advanced property flags:
Object.defineProperty(Window.prototype, "open", {value: wrapper, configurable: false});
The webpage can no longer revert this change but it can still detect it: delete Window.prototype.open normally changes the value of Window.prototype.open (different instance of the same function it seems), here delete won't have any effect at all. Also, Window.prototype.open = "test";delete Window.prototype.open; will produce inconsistent results (different ones depending on whether writable: false flag is specified for the property).
Is there anything else that I can do to emulate the behavior of the original property (short of using binary XPCOM components which has way too many issues of its own)?