RegExpMacroAssembler::CheckStackGuardState should update input string pointer

RegExpMacroAssembler::CheckStackGuardState should update input string pointer when it is moved or changed by GC.

If input string was cons-string it might undergo short-circuiting during GC. This does not change input start if underlying seq-string (first element of cons-string) does not move but this makes input-string pointer on the native regexp's frame invalid.

R=lrn@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=9697

[Lasse Reichstein, 2011-10-19 07:40:04]

LGTM