[heap] Remove allocation step from FreeList::Allocate

This avoids double accounting since we also have the call in the bottleneck.

R=hpayer@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2206623003
Cr-Commit-Position: refs/heads/master@{#38281}

src/heap/spaces.cc

@@ -2516,8 +2516,6 @@ HeapObject* FreeList::Allocate(int size_in_bytes) {
                               new_node->address() + new_node_size);
   }
 
-  owner_->AllocationStep(new_node->address(), size_in_bytes);
-
   return new_node;
 }