HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {

  {- -------------------------------------------
  (1) GenCollectedHeap::mem_allocate() を呼び出し, その結果をリターンするだけ.
      ---------------------------------------- -}

      bool gc_overhead_limit_was_exceeded;
      HeapWord* result = mem_allocate(size   /* size */,
                                      false  /* is_large_noref */,
                                      true   /* is_tlab */,
                                      &gc_overhead_limit_was_exceeded);
      return result;
    }