jscript: Fixed Math.round with no argument.

dlls/jscript/math.c

@@ -381,8 +381,8 @@ static HRESULT Math_round(DispatchEx *dispex, LCID lcid, WORD flags, DISPPARAMS
     TRACE("\n");
 
     if(!arg_cnt(dp)) {
-        FIXME("arg_cnt = 0\n");
-        return E_NOTIMPL;
+        num_set_nan(retv);
+        return S_OK;
     }
 
     hres = to_number(dispex->ctx, get_arg(dp, 0), ei, &v);

dlls/jscript/tests/api.js

@@ -519,6 +519,9 @@ ok(tmp === 1, "Math.round(true) = " + tmp);
 tmp = Math.round(1.1, 3, 4);
 ok(tmp === 1, "Math.round(1.1, 3, 4) = " + tmp);
 
+tmp = Math.round();
+ok(isNaN(tmp), "Math.round() is not NaN");
+
 tmp = Math.ceil(0.5);
 ok(tmp === 1, "Math.ceil(0.5) = " + tmp);