Not true: Javascript borderColor is supported by FF, however, document.all is MSFT proprietary introduced in Internet Explorer 4 and replaced (IE still retains legacy support) by document.all in IE5, Opera6, NN6, Moz/FF and subsequent browsers.
Unless you expect IE4 users you can safely discontinue document.all.
Possible problem - id must be unique, one per page (each td would need its own id) - so your code is closer to requiring document.getElementsByTagName.
Or use CSS and a function similar to following: