Always trace garbage collection events in GCTracer.

- always trace events in GCTracer, but only print stats when the command
  line flag is set.
- required to collect statistis that will be used to schedue garbage
  collection.
- we need to watch the perf bots after this lands, as it could regress
  performance.

R=hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/410413007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22613 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
In GrowMode, force the value to the right representation to avoid deopts between storing the length and storing the value.

BUG=16459193
LOG=n
R=danno@chromium.org

Review URL: https://codereview.chromium.org/419683004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22616 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Smi arrays are only guaranteed to be initialized in non-holey case

BUG=
R=ishell@chromium.org

Review URL: https://codereview.chromium.org/413393004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22617 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
[Auto-roll] Bump up version to 3.28.39.0

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/416333005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22618 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Kraken recover after r20312.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/416393002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22620 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/bleeding_edge' into bleeding_edge