Additional minor cleanup regarding CallWrapper: Use the null object pattern.

Additional minor cleanup regarding CallWrapper: Use the null object pattern.
Committed: http://code.google.com/p/v8/source/detail?r=7767

[Kevin Millikin (Chromium), 2011-05-03 14:19:20]

LGTM.  You could put the default behavior in the base class instead of making
the member functions pure virtual---that would allow subclasses to override one
but not both of before/after.

[Sven Panne, 2011-05-03 15:06:05]

On 2011/05/03 14:19:20, Kevin Millikin wrote:
> LGTM.  You could put the default behavior in the base class instead of making
the member functions pure virtual---that would allow subclasses to override one
but not both of before/after.

I thought about this, too, but in the end I find the clear separation into a
pure interface and its implementations more aesthetically pleasing. If you're
lazy, you could subclass NullCallWrapper... ;-)

[danno, 2011-05-05 14:21:44]

LGTM