8327130: Serial: Remove Generation::record_spaces_top

Reviewed-by: gli, kbarrett

src/hotspot/share/gc/serial/defNewGeneration.hpp

@@ -234,7 +234,7 @@ class DefNewGeneration: public Generation {
   void gc_epilogue(bool full);
 
   // Save the tops for eden, from, and to
-  virtual void record_spaces_top();
+  void record_spaces_top();
 
   // Accessing marks
   void save_marks();

src/hotspot/share/gc/serial/generation.hpp

@@ -168,9 +168,6 @@ class Generation: public CHeapObj<mtGC> {
   // still unsuccessful, return "null".
   virtual HeapWord* expand_and_allocate(size_t word_size, bool is_tlab) = 0;
 
-  // Save the high water marks for the used space in a generation.
-  virtual void record_spaces_top() {}
-
   // Generations may keep statistics about collection. This method
   // updates those statistics. current_generation is the generation
   // that was most recently collected. This allows the generation to

src/hotspot/share/gc/serial/tenuredGeneration.hpp

@@ -154,7 +154,7 @@ class TenuredGeneration: public Generation {
   // Performance Counter support
   void update_counters();
 
-  virtual void record_spaces_top();
+  void record_spaces_top();
 
   // Statistics