Get rid of ZoneScope completely.

Get rid of ZoneScope completely.

There's no need to differentiate between an actual Zone and its
scope. Instead we bind the lifetime of the Zone memory to the
lifetime of the Zone itself, which is way easier to understand
than having to dig through the code looking for zone scopes.

Depends on https://codereview.chromium.org/17826004/

R=danno@chromium.org
BUG=

Committed: https://code.google.com/p/v8/source/detail?r=15337

[Benedikt Meurer, 2013-06-26 12:50:13]

This is a huge cleanup, making it way easier to understand the actual lifetime
of zone allocations, as this is now explicitly bound to the lifetime of the Zone
itself, not some arbitrary ZoneScope.

The benchmark results for ia32.release on Linux show 0.4% for Octane, 0.5% for
Kraken-Orig and 1.9% for SunSpider-Orig.

[danno, 2013-06-26 13:06:58]

lgtm with comments I am not so certain about the benchmark wins. I also am a bit
concerned about completely removing the logic that recycles segments. It may not
show up in the core benchmarks, but keep an eye on other benchmarks to verify
that there are really no regressions.

https://codereview.chromium.org/17827005/diff/1/src/json-parser.h
File src/json-parser.h (right):

https://codereview.chromium.org/17827005/diff/1/src/json-parser.h#newcode325
src/json-parser.h:325: ZoneList<Handle<Object> > properties(8, &zone_);
here an else where, does it make sense to wrap zone_ in a simple accessor
function zone()?

https://codereview.chromium.org/17827005/diff/1/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/17827005/diff/1/src/runtime.cc#newcode6322
src/runtime.cc:6322: FindStringIndicesDispatch(isolate,
nit: Group multiple arguments per line,  this burns too many lines and doesn't
improve readability.

[Benedikt Meurer, 2013-06-26 13:34:38]

https://codereview.chromium.org/17827005/diff/1/src/json-parser.h
File src/json-parser.h (right):

https://codereview.chromium.org/17827005/diff/1/src/json-parser.h#newcode325
src/json-parser.h:325: ZoneList<Handle<Object> > properties(8, &zone_);
On 2013/06/26 13:06:58, danno wrote:
> here an else where, does it make sense to wrap zone_ in a simple accessor
> function zone()?

Done.

https://codereview.chromium.org/17827005/diff/1/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/17827005/diff/1/src/runtime.cc#newcode6322
src/runtime.cc:6322: FindStringIndicesDispatch(isolate,
On 2013/06/26 13:06:58, danno wrote:
> nit: Group multiple arguments per line,  this burns too many lines and doesn't
> improve readability.

Done.

[Benedikt Meurer, 2013-06-26 13:36:34]

Committed patchset #2 manually as r15337 (presubmit successful).