G1: Use SoftMaxHeapSize to guide GC heuristics

*** 1207,1218 ****
      if (ClassUnloadingWithConcurrentMark) {
        GCTraceTime(Debug, gc, phases) debug("Purge Metaspace", _gc_timer_cm);
        ClassLoaderDataGraph::purge();
      }
  
-     _g1h->resize_heap_if_necessary();
- 
      compute_new_sizes();
  
      verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark after");
  
      assert(!restart_for_overflow(), "sanity");
--- 1207,1216 ----
*** 1380,1389 ****
--- 1378,1392 ----
  
    // We need to make this be a "collection" so any collection pause that
    // races with it goes around and waits for Cleanup to finish.
    _g1h->increment_total_collections();
  
+   {
+     GCTraceTime(Debug, gc, phases) debug("Expand heap after concurrent mark", _gc_timer_cm);
+     _g1h->expand_heap_after_concurrent_mark();
+   }
+ 
    // Local statistics
    double recent_cleanup_time = (os::elapsedTime() - start);
    _total_cleanup_time += recent_cleanup_time;
    _cleanup_times.add(recent_cleanup_time);