Make ZoneObject::operator delete not public.

Make ZoneObject::operator delete not public.

This prevents a n00b mistake of just calling delete on a ZoneObject subclass
compile time rather than run time. (Sadly, it doesn't work for second-level
subclasses and beyond.)

BUG=

[ulan, 2014-01-29 15:42:10]

lgtm

[tfarina, 2014-01-29 17:39:15]

https://codereview.chromium.org/141553007/diff/60001/src/zone.h
File src/zone.h (right):

https://codereview.chromium.org/141553007/diff/60001/src/zone.h#newcode146
src/zone.h:146: // Ideally, the delete operator should be private instead of
can you update this comment while you are here?

[marja, 2014-01-29 17:42:18]

https://codereview.chromium.org/141553007/diff/60001/src/zone.h
File src/zone.h (right):

https://codereview.chromium.org/141553007/diff/60001/src/zone.h#newcode146
src/zone.h:146: // Ideally, the delete operator should be private instead of
On 2014/01/29 17:39:15, tfarina wrote:
> can you update this comment while you are here?

Actually... I should've read the "MSVC requires the delete operator to be
public" part. It makes this CL pointless. Nevermind. Closing. Thanks for
pointing out the comment.

[tfarina, 2014-01-29 17:43:42]

https://codereview.chromium.org/141553007/diff/60001/src/zone.h
File src/zone.h (right):

https://codereview.chromium.org/141553007/diff/60001/src/zone.h#newcode236
src/zone.h:236: void operator delete(void* pointer) { UNREACHABLE(); }
do you want to make these and the ZoneSplayTree ones protected as well?

[tfarina, 2014-01-29 17:45:00]

https://codereview.chromium.org/141553007/diff/60001/src/zone.h
File src/zone.h (right):

https://codereview.chromium.org/141553007/diff/60001/src/zone.h#newcode146
src/zone.h:146: // Ideally, the delete operator should be private instead of
On 2014/01/29 17:42:18, marja wrote:
> On 2014/01/29 17:39:15, tfarina wrote:
> > can you update this comment while you are here?
> 
> Actually... I should've read the "MSVC requires the delete operator to be
> public" part. It makes this CL pointless. Nevermind. Closing. Thanks for
> pointing out the comment.
So disregards my latest comment in src/zone.h:236 ;-)