8020277: Young GC could be extremely slow due to assertion in ObjectStartArray::object_starts_in_range

8009462: Young GC's (ParNewGC and SerialGC) have unexpected variances

Removed the assertion slowing down GC.

Reviewed-by: stefank, mgerdin

hotspot/src/share/vm/gc_implementation/parallelScavenge/objectStartArray.cpp

@@ -139,11 +139,6 @@ bool ObjectStartArray::object_starts_in_range(HeapWord* start_addr,
       return true;
     }
   }
-  // No object starts in this slice; verify this using
-  // more traditional methods:  Note that no object can
-  // start before the start_addr.
-  assert(end_addr == start_addr ||
-         object_start(end_addr - 1) <= start_addr,
-         "Oops an object does start in this slice?");
+
   return false;
 }