The Tor Browser / file revision

 // env.find throws a TypeError if the argument is not an identifier.

 load(libdir + "asserts.js");

 var g = newGlobal();

 var dbg = Debugger(g);

 var hits = 0;

 g.h = function () {

     var env = dbg.getNewestFrame().environment;

     assertThrowsInstanceOf(function () { env.find(); }, TypeError);

     assertThrowsInstanceOf(function () { env.find(""); }, TypeError);

     assertThrowsInstanceOf(function () { env.find(" "); }, TypeError);

     assertThrowsInstanceOf(function () { env.find(0); }, TypeError);

     assertThrowsInstanceOf(function () { env.find("0"); }, TypeError);

     assertThrowsInstanceOf(function () { env.find("0xc"); }, TypeError);

     assertThrowsInstanceOf(function () { env.find("Anna Karenina"); }, TypeError);

     hits++;

 };

 g.eval("h();");

 g.eval("with ([1]) h();");

 assertEq(hits, 2);