Fix issue 982.

Fix issue 982.

When splitting at the beginning of a use interval assign coinciding position to the split child instead of leaving it to parent.

BUG=v8:982
Committed: http://code.google.com/p/v8/source/detail?r=6031

[Kevin Millikin (Chromium), 2010-12-15 14:01:52]

LGTM.

http://codereview.chromium.org/5898001/diff/1/src/lithium-allocator.cc
File src/lithium-allocator.cc (right):

http://codereview.chromium.org/5898001/diff/1/src/lithium-allocator.cc#newcod...
src/lithium-allocator.cc:300: // If split position coincides with the beginning
of use interval
"the split position"..."a use interval" :)

http://codereview.chromium.org/5898001/diff/1/src/lithium-allocator.cc#newcod...
src/lithium-allocator.cc:331: while (use_after != NULL &&
use_after->pos().Value() < position.Value()) {
Maybe this case needs a short comment too, something like "We are splitting at
the start of an interval.  The use position at the start of the interval belongs
after the split."