https://bugs.webkit.org/show_bug.cgi?id=87401

Reviewed by Oliver Hunt.

This allows us fast access to the set of all weak pointers for a block,
which is a step toward lazy finalization.

No performance change.

* heap/Heap.cpp:
(JSC::Heap::Heap):
(JSC::Heap::lastChanceToFinalize): Removed the per-heap weak set, since
it's per-block now.

(JSC::Heap::markRoots): Delegate weak set visiting to the marked space,
since it knows how to iterate all blocks.

(JSC::Heap::collect): Moved the reaping outside of markRoots, since it
doesn't mark anything.

Make sure to reset allocators after shrinking, since shrinking may
deallocate the current allocator.

* heap/Heap.h:
(Heap): No more per-heap weak set, since it's per-block now.

* heap/MarkedBlock.cpp:
(JSC::MarkedBlock::MarkedBlock):
* heap/MarkedBlock.h:
(MarkedBlock):
(JSC::MarkedBlock::lastChanceToFinalize): Migrated finalization logic
here from the heap, so the heap doesn't need to know about our internal
data structures like our weak set.

(JSC::MarkedBlock::heap):
(JSC::MarkedBlock::weakSet):
(JSC::MarkedBlock::shrink):
(JSC::MarkedBlock::resetAllocator):
(JSC::MarkedBlock::visitWeakSet):
(JSC::MarkedBlock::reapWeakSet):
(JSC::MarkedBlock::sweepWeakSet):
* heap/MarkedSpace.cpp:
(JSC::VisitWeakSet::VisitWeakSet):
(JSC::VisitWeakSet::operator()):
(VisitWeakSet):
(JSC):
(JSC::ReapWeakSet::operator()):
(JSC::SweepWeakSet::operator()):
(JSC::LastChanceToFinalize::operator()):
(JSC::MarkedSpace::lastChanceToFinalize):
(JSC::ResetAllocator::operator()):
(JSC::MarkedSpace::resetAllocators):
(JSC::MarkedSpace::visitWeakSets):
(JSC::MarkedSpace::reapWeakSets):
(JSC::MarkedSpace::sweepWeakSets):
(JSC::Shrink::operator()):
(JSC::MarkedSpace::shrink):
* heap/MarkedSpace.h:
(MarkedSpace): Make sure to account for our weak sets when sweeping,
shrinking, etc.

* heap/WeakSet.cpp:
(JSC):
* heap/WeakSet.h:
(WeakSet):
(JSC::WeakSet::heap):
(JSC):
(JSC::WeakSet::lastChanceToFinalize):
(JSC::WeakSet::visit):
(JSC::WeakSet::reap):
(JSC::WeakSet::shrink):
(JSC::WeakSet::resetAllocator): Inlined some things since they're called
once per block now instead of once per heap.

* heap/WeakSetInlines.h:
(JSC::WeakSet::allocate): Use the per-block weak set since there is no
per-heap weak set anymore.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@118416 268f45cc-cd09-0410-ab3c-d52691b4dbfc