Remove deprecated RenderArena object and fix stack source path.

Remove deprecated RenderArena object and fix stack source path.
    
RenderArena object is deprecated in WebCore.
And WebCore path has been changed from WebCore to core.

BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=282306

[JungJik, 2014-07-10 01:44:58]

PTAL :)

[Dai Mikurube (NOT FULLTIME), 2014-07-10 04:14:04]

lgtm. Thanks!

[JungJik, 2014-07-10 05:01:02]

The CQ bit was checked by jungjik.lee@samsung.com

[JungJik, 2014-07-10 05:01:05]

The CQ bit was unchecked by jungjik.lee@samsung.com

[JungJik, 2014-07-10 05:02:23]

The CQ bit was checked by jungjik.lee@samsung.com

[commit-bot: I haz the power, 2014-07-10 05:03:11]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jungjik.lee@samsung.com/352113002/20001

[Dai Mikurube (NOT FULLTIME), 2014-07-10 05:25:50]

For changes under tools/deep_memory_profiler, you may want to specify NOTRY=True
in the commit description. dmprof doesn't affect any buildbot. Triggering
trybots just wastes time. :)

[JungJik, 2014-07-10 06:29:14]

On 2014/07/10 05:25:50, Dai Mikurube wrote:
> For changes under tools/deep_memory_profiler, you may want to specify
NOTRY=True
> in the commit description. dmprof doesn't affect any buildbot. Triggering
> trybots just wastes time. :)

thanks for guide. I will add it next time. :)

[commit-bot: I haz the power, 2014-07-10 11:08:26]

Change committed as 282306