The Tor Browser / file revision

 var f1 = function f0(a, b) { return a + b; }

 assertEq(f1.toSource(), "(function f0(a, b) { return a + b; })");

 assertEq(f1.toString(), "function f0(a, b) { return a + b; }");

 assertEq(decompileFunction(f1), f1.toString());

 assertEq(decompileBody(f1), " return a + b; ");

 var f2 = function (a, b) { return a + b; };

 assertEq(f2.toSource(), "(function (a, b) { return a + b; })");

 assertEq(f2.toString(), "function (a, b) { return a + b; }");

 assertEq(decompileFunction(f2), f2.toString());

 assertEq(decompileBody(f2), " return a + b; ");

 var f3 = (function (a, b) { return a + b; });

 assertEq(f3.toSource(), "(function (a, b) { return a + b; })");

 assertEq(f3.toString(), "function (a, b) { return a + b; }");

 assertEq(decompileFunction(f3), f3.toString());

 assertEq(decompileBody(f3), " return a + b; ");