There are plenty of languages which have an (implicit or explicit) argument called something like "this" or "self" where the semantics of a x.y() call are "look up y on the x object, call it with x as the this argument". C++ fundamentally works like that (the look-up is compile time in the case of non-virtual functions, but like JS at runtime for virtual functions), Python, Java, etc.
The oddity with JavaScript is two-fold: firstly, the fact that it passes the global object (in non-strict code) given an z() style call (v. x.y() above); secondly, the fact that you can call a function with an explicit this argument using Array.prototype.call or Array.prototype.array.
What feels far more odd than that, though, is what the DOM does. It often acts as if there's been a method call, whereas in reality it's just called with an explicit this argument from C++. If you view a method dispatch as being a message (à la Smalltalk, a large influence on JS) then obviously an event's target is invoked as a message to the event. I obviously can't comment if that's what Brendan was thinking, but it seems like an obvious analogue.
Is there any other language that uses "this" to denote "current context"?