Allow viewing a given version of a file from the log page

[GoogleCodeExporter]

When looking at a log of a particular file (say 
https://chromium.googlesource.com/chromium/src/+log/master/chrome/browser/chrome
_browser_main.cc), there should be a way to jump directly to what that 
particular file looked like at any given version.

Something that I frequently do before looking at the blame for a given version 
is to scan the list of changes that touch a file until I find something that is 
relevant and then take it from there.

In fact, maybe I rely on that functionality from http://src.chromium.org/viewvc 
even more than actual blame.

Original issue reported on code.google.com by rvargas@chromium.org on 5 May 2014 at 6:32

[GoogleCodeExporter]

Agreed, analogous to how we have extra [blame] links on the /+diff page when 
the path is a single file.

(Sorry that log page is so slow BTW...just learned today JGit is about 20x 
slower than C git on log of a file.)

Original comment by dborowitz@google.com on 5 May 2014 at 6:48