Add a little script for resurrecting pre-fork Blink files

Since Sky is checked directly into mojo and does not contain
Blink history, I knew of no easy way to resurrect Blink files.

In making the V8 debugger work, I had to bring back a ton
of files and thus wrote a script to help me do so.

Maybe others will find this useful.

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/732193002