Unfortunately no browser is yet sufficiently bug-free for a frequent user not to hit bugs pretty frequently... Eg. last week Chrome kept displaying graphical glitches wherever webgl content should render...
Saying "yet" almost implies there's supposed to be progress towards it?
If anything, I think there's been regress. There was a time, long past, when I didn't really have to think about the browser itself much at all. It just did its job and problems were rare. Browsers and the web have turned enormously complex now. WebGL is a case in point: it's complex by itself, and it also brings in all the complexity of the graphics drivers & GL implementation on your system. Graphics drivers are the most complex of all drivers on your system, and GPUs are the least reliable of your components..
