Refactors parts of gin:
. Runner no longer extends ContextHolder. It will still have a
  ContextHolder, but not own it. This enables a couple of
  things:
  . Runner no longer need own a v8::Context.
  . Runner can be lazily created after the ContextHolder.
. Runner becomes a (mostly) pure virtual interface. This enables an
  implementation to execute through blink rather than v8 directly.
. What was Runner is now DefaultRunner (and
  DefaultRunnerDelegate). I'm not a fan of these names, if you have
  better ideas let me know. Maybe DirectRunner?

BUG=none
TEST=none
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/179803007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253732 0039d316-1c4b-4281-b951-d872f2087c98
Update nss_revision to 253292.

Includes the following CLs:

Revert r228205.
> Disable optimization in prdtoa.c under VS2013.
https://codereview.chromium.org/180233003/

R=scottmg@chromium.org
BUG=none
TEST=none

Review URL: https://codereview.chromium.org/181383007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253733 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253734 0039d316-1c4b-4281-b951-d872f2087c98
Always broadcast one last "tab not blocked" notification before closing a tab.

BUG=336386
TEST=as in bug

Review URL: https://codereview.chromium.org/132103005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253735 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253734
SVN changes up to revision 253735