Revert of Fix old space check in IsSlotInBlackObject. (patchset #1 id:1 of...

Revert of Fix old space check in IsSlotInBlackObject. (patchset #1 id:1 of https://codereview.chromium.org/993513009/)

Reason for revert:
Breaks arm.debug.

Original issue's description:
> Fix old space check in IsSlotInBlackObject.
>
> BUG=
>
> Committed: https://crrev.com/4f865389bcecdff6aa56512fab3a147507a95a51
> Cr-Commit-Position: refs/heads/master@{#27090}

TBR=ulan@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/987303003

Cr-Commit-Position: refs/heads/master@{#27095}

src/heap/mark-compact.cc

@@ -3059,8 +3059,7 @@ bool MarkCompactCollector::TryPromoteObject(HeapObject* object,
 
 bool MarkCompactCollector::IsSlotInBlackObject(Page* p, Address slot) {
   // This function does not support large objects right now.
-  Space* owner = p->owner();
-  if (owner == heap_->lo_space() || owner == NULL) return true;
+  if (p->owner() == NULL) return true;
 
   uint32_t mark_bit_index = p->AddressToMarkbitIndex(slot);
   unsigned int start_index = mark_bit_index >> Bitmap::kBitsPerCellLog2;