Avoid allocation of temporary zone lists when inserting representation change...

Avoid allocation of temporary zone lists when inserting representation changes.

Instead of allocating fresh temporary lists for every instruction, reuse
the same instance and reset it between instructions.

This reduces the amount of zone memory used for inserting the HChange
instructions roughly by half.


Committed: http://code.google.com/p/v8/source/detail?r=7094

[Kevin Millikin (Chromium), 2011-03-08 14:31:34]

LVGTM.