Heavy external fragmentation in FixedVMPoolAllocator can lead to a CRASH().

Reviewed by Geoff Garen.

The FixedVMPoolAllocator currently uses a best fix policy -
switch to first fit, this is less prone to external fragmentation.

* jit/ExecutableAllocatorFixedVMPool.cpp:
(JSC::AllocationTableSizeClass::AllocationTableSizeClass):
(JSC::AllocationTableSizeClass::blockSize):
(JSC::AllocationTableSizeClass::blockCount):
(JSC::AllocationTableSizeClass::blockAlignment):
(JSC::AllocationTableSizeClass::size):
(JSC::AllocationTableLeaf::AllocationTableLeaf):
(JSC::AllocationTableLeaf::~AllocationTableLeaf):
(JSC::AllocationTableLeaf::allocate):
(JSC::AllocationTableLeaf::free):
(JSC::AllocationTableLeaf::isEmpty):
(JSC::AllocationTableLeaf::isFull):
(JSC::AllocationTableLeaf::size):
(JSC::AllocationTableLeaf::classForSize):
(JSC::AllocationTableLeaf::dump):
(JSC::LazyAllocationTable::LazyAllocationTable):
(JSC::LazyAllocationTable::~LazyAllocationTable):
(JSC::LazyAllocationTable::allocate):
(JSC::LazyAllocationTable::free):
(JSC::LazyAllocationTable::isEmpty):
(JSC::LazyAllocationTable::isFull):
(JSC::LazyAllocationTable::size):
(JSC::LazyAllocationTable::dump):
(JSC::LazyAllocationTable::classForSize):
(JSC::AllocationTableDirectory::AllocationTableDirectory):
(JSC::AllocationTableDirectory::~AllocationTableDirectory):
(JSC::AllocationTableDirectory::allocate):
(JSC::AllocationTableDirectory::free):
(JSC::AllocationTableDirectory::isEmpty):
(JSC::AllocationTableDirectory::isFull):
(JSC::AllocationTableDirectory::size):
(JSC::AllocationTableDirectory::classForSize):
(JSC::AllocationTableDirectory::dump):
(JSC::FixedVMPoolAllocator::FixedVMPoolAllocator):
(JSC::FixedVMPoolAllocator::alloc):
(JSC::FixedVMPoolAllocator::free):
(JSC::FixedVMPoolAllocator::allocated):
(JSC::FixedVMPoolAllocator::isValid):
(JSC::FixedVMPoolAllocator::classForSize):
(JSC::FixedVMPoolAllocator::offsetToPointer):
(JSC::FixedVMPoolAllocator::pointerToOffset):
(JSC::ExecutableAllocator::committedByteCount):
(JSC::ExecutableAllocator::isValid):
(JSC::ExecutableAllocator::underMemoryPressure):
(JSC::ExecutablePool::systemAlloc):
(JSC::ExecutablePool::systemRelease):
* wtf/PageReservation.h:
(WTF::PageReservation::PageReservation):
(WTF::PageReservation::commit):
(WTF::PageReservation::decommit):
(WTF::PageReservation::committed):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@77025 268f45cc-cd09-0410-ab3c-d52691b4dbfc