Reuse the gap move resolver.

Reuse the gap move resolver.

Rather than allocating a fresh gap move resolver for every parallel
move, use a single one per Lithium code generator.  This avoids always
reallocating the temporary zone-allocated lists used by the gap move
resolver.

Committed: http://code.google.com/p/v8/source/detail?r=6270

[Kevin Millikin (Chromium), 2011-01-10 13:38:40]

This simple change cuts zone allocation for Lithium code generation on the
benchmarks from 7.2 MB to 2.3 MB.

[fschneider, 2011-01-11 11:25:18]

LGTM!