src/third_party/mozjs-45/js/src/jit-test/tests/debug/Frame-environment-01.js

// frame.environment is a Debugger.Environment object

var g = newGlobal()
var dbg = Debugger(g);
g.h = function () {
    assertEq(dbg.getNewestFrame().environment instanceof Debugger.Environment, true);
};

g.eval("h()");
g.evaluate("h()");
g.eval("eval('h()')");
g.eval("function f() { h(); }");
g.f();