mozilla/servo — pull request #720 by ILyoan (2013-08-12 08:29:56+00:00)
Title: Implement GetElementById

This implements document.getElementById().

`Element.GetAttribute()` function is called in the middle of this implementation and that function simply returns `null_string`. but once the function implemented properly, `GetElementById()` would work.
PR #719 contains the implementation of `Element.GetAttribute()` (892e248).