2011-05-25 Oliver Hunt <oliver@apple.com>

2011-05-25  Oliver Hunt  <oliver@apple.com>

        Reviewed by Geoffrey Garen.

        Make allocations with guard pages ensure that the allocation succeeded
        https://bugs.webkit.org/show_bug.cgi?id=61453

        Add null checks, and make PageBlock's operator bool() use
        the realbase, rather than the start of usable memory.

        * wtf/OSAllocatorPosix.cpp:
        (WTF::OSAllocator::reserveAndCommit):
        * wtf/PageBlock.h:
        (WTF::PageBlock::operator bool):
        (WTF::PageBlock::PageBlock):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@87308 268f45cc-cd09-0410-ab3c-d52691b4dbfc