The Tor Browser / file revision

 // We correctly reject bogus for-of loop syntax.

 load(libdir + "asserts.js");

 function assertSyntaxError(code) {

     assertThrowsInstanceOf(function () { Function(code); }, SyntaxError, "Function:" + code);

     assertThrowsInstanceOf(function () { eval(code); }, SyntaxError, "eval:" + code);

     var ieval = eval;

     assertThrowsInstanceOf(function () { ieval(code); }, SyntaxError, "indirect eval:" + code);

 }

 function test(badForHead) {

     assertSyntaxError(badForHead + " {}");  // apply directly to forHead

     assertSyntaxError("[0 " + badForHead + "];");

 }

 var a, b, c;

 test("for (a in b of c)");

 test("for each (a of b)");

 test("for (a of b of c)");

 test("for (let (a = 1) a of b)");

 test("for (let {a: 1} of b)");