8038628: Remove unused Closure::abort()

Reviewed-by: coleenp, jmasa

hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp

@@ -472,9 +472,6 @@ HeapRegion::object_iterate_mem_careful(MemRegion mr,
     } else if (!g1h->is_obj_dead(obj)) {
       cl->do_object(obj);
     }
-    if (cl->abort()) return cur;
-    // The check above must occur before the operation below, since an
-    // abort might invalidate the "size" operation.
     cur += obj->size();
   }
   return NULL;

hotspot/src/share/vm/memory/iterator.hpp

@@ -30,8 +30,6 @@
 #include "runtime/prefetch.hpp"
 #include "utilities/top.hpp"
 
-// The following classes are C++ `closures` for iterating over objects, roots and spaces
-
 class CodeBlob;
 class nmethod;
 class ReferenceProcessor;
@@ -39,22 +37,11 @@ class DataLayout;
 class KlassClosure;
 class ClassLoaderData;
 
-// Closure provides abortability.
+// The following classes are C++ `closures` for iterating over objects, roots and spaces
 
-class Closure : public StackObj {
+class Closure : public StackObj { };
- protected:
-  bool _abort;
-  void set_abort() { _abort = true; }
- public:
-  Closure() : _abort(false) {}
-  // A subtype can use this mechanism to indicate to some iterator mapping
-  // functions that the iteration should cease.
-  bool abort() { return _abort; }
-  void clear_abort() { _abort = false; }
-};
 
 // OopClosure is used for iterating through references to Java objects.
-
 class OopClosure : public Closure {
  public:
   virtual void do_oop(oop* o) = 0;