Applied the patch for bug 58837 (for the mysql-5.6 code line).

This patch fixed the crash in innodb_bug59307.

sql/handler.h

@@ -1716,6 +1716,7 @@ class handler :public Sql_alloc
     DBUG_ENTER("ha_rnd_init");
     DBUG_ASSERT(inited==NONE || (inited==RND && scan));
     inited= (result= rnd_init(scan)) ? NONE: RND;
+    end_range= NULL;
     DBUG_RETURN(result);
   }
   int ha_rnd_end()
@@ -1723,6 +1724,7 @@ class handler :public Sql_alloc
     DBUG_ENTER("ha_rnd_end");
     DBUG_ASSERT(inited==RND);
     inited=NONE;
+    end_range= NULL;
     DBUG_RETURN(rnd_end());
   }
   int ha_rnd_init_with_error(bool scan) __attribute__ ((warn_unused_result));