This reverts commit 7bb1d38.

When we round up, we introduce the risk that the new size exceeds the
maximum LAB size, resulting in an assertion error.

This reverts commit 99cce53.

This reverts commit d881300.

This may allow us to reclaim immediate garbage more quickly.

We just reported freeset status after rebuilding freeset in final mark.
There will be heavy contention on the heaplock at the start of
evacuation as many mutator and worker threads prep their GCLAB and PLAB
buffers for evacuation.  We avoid some lock contention by not reporting
freset status here.

If we notify waiting mutators after immediate garbage is reclaimed, do
not clear the alloc-failure flag.  Otherwise, this hides the fact that
alloc failure occurred during this GC.