WebCore can call kjs_strtod without holding JS lock, but we didn't have thread safety
compiled in for dtoa.
This is a 0.5% regression on SunSpider, which Sam Weinig has volunteered to cover with
his recent improvement.
kjs/dtoa.cpp:
(Bigint::Balloc):
(Bigint::Bfree):
Changed to use fastMalloc/fastDelete - they are much faster than the dtoa custom version was
in the presence of locking (but somewhat slower in single-threaded case).
(Bigint::pow5mult): Got rid of the dreaded double-checked locking anti-pattern (had to
restructure the code to avoid significant performance implications).
(Bigint::lshift): Rewrote to avoid an allocation, if possible.
(Bigint::rv_alloc):
(Bigint::kjs_freedtoa):
(Bigint::kjs_dtoa):
Check for USE(MULTIPLE_THREADS), not dtoa legacy MULTIPLE_THREADS.
wtf/Threading.h: Removed a using directive for WTF::initializeThreading - it is only
to be called from KJS::initializeThreading, and having it in the global namespace is useless.
