The Tor Browser / file revision

 // uncaughtExceptionHook returns a resumption value.

 load(libdir + "asserts.js");

 var g = newGlobal();

 var dbg = new Debugger(g);

 var rv;

 dbg.onDebuggerStatement = function () { throw 15; };

 dbg.uncaughtExceptionHook = function (exc) {

     assertEq(exc, 15);

     return rv;

 };

 // case 1: undefined

 rv = undefined;

 g.eval("debugger");

 // case 2: throw

 rv = {throw: 57};

 var result;

 assertThrowsValue(function () { g.eval("debugger"); }, 57);

 // case 3: return

 rv = {return: 42};

 assertEq(g.eval("debugger;"), 42);