deps: upgrade to V8 4.7.80.24
Ref: #4085
Now that V8 4.7 has hit stable [0], this PR brings V8 4.7 onto master.
The PR includes all the cherry-picks from vee-eight-4.7
annd additionally 70405d47 was cherry-picked back from master
.
Full change history for the 4.7 branch: https://chromium.googlesource.com/v8/v8.git/+log/branch-heads/4.7
V8 blog post about what is new on V8 4.7: http://v8project.blogspot.de/2015/10/v8-release-47.html
R=@bnoordhuis, @targos /cc @misterdjules, @nodejs/v8 /cc @nodejs/build as this probably effects beta builds.
[0] http://googlechromereleases.blogspot.com/2015/12/stable-channel-update.html