RFR: Remove obsolete check in FreeSet::allocate

[Aleksey Shipilev]

There is an obsolete check in FreeSet::allocate, that stopped being relevant after we did allocation
bitmaps. There is no "current_index" to trust now.

diff -r 2416e01eb9b9 src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp	Thu Mar 29 14:25:47 2018 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp	Thu Mar 29 16:08:58 2018 +0200
@@ -428,11 +428,6 @@
   assert_heaplock_owned_by_current_thread();
   assert_bounds();

-  // Not enough memory in free region set. Coming out of full GC, it is possible that
-  // there are no free regions available, so current_index may be invalid. Have to
-  // poll capacity as the precaution here.
-  if (word_size * HeapWordSize > capacity()) return NULL;
-
   if (word_size > ShenandoahHeapRegion::humongous_threshold_words()) {
     switch (type) {
       case ShenandoahHeap::_alloc_shared:

Testing: hotspot_gc_shenandoah

Thanks,
-Aleksey