Configurable vector capacity in blink::DistributedNodes

Configurable vector capacity in blink::DistributedNodes

This patch allows setting initial vector capacity in blink::DistributedNodes.
It improves the results of the 'LargeDistributionWithoutLayout.html' performance test approximately by 4% (Linux desktop x64).

before:
avg 299.6348742769932 runs/s
median 299.50975629463005 runs/s
stdev 2.05745824437092 runs/s
min 295.2029520295203 runs/s
max 303.323285749493 runs/s

after:
avg 310.3259225820019 runs/s
median 312.8024733902208 runs/s
stdev 6.222720323148261 runs/s
min 298.0681458298404 runs/s
max 317.88500509940576 runs/s

[Mikhail, 2015-07-24 07:38:15]

mikhail.pozdnyakov@intel.com changed reviewers:
+ hayato@chromium.org

[Mikhail, 2015-07-24 10:30:26]

PTAL

[hayato, 2015-07-27 08:03:29]

I'm afraid that we don't get meaningful benefits from this CL.
LargeDistributionWithoutLayout was introduced as a micro bench mark to catch a
regression. We don't need to improve the result of this benchmark.

Do we have any improvement other than the result of this benchmark?

[Mikhail, 2015-07-28 13:28:00]

On 2015/07/27 08:03:29, hayato wrote:
> I'm afraid that we don't get meaningful benefits from this CL.
> LargeDistributionWithoutLayout was introduced as a micro bench mark to catch a
> regression. We don't need to improve the result of this benchmark.
> 
> Do we have any improvement other than the result of this benchmark?

Not really. Thanks for having a look.