updated for version 7.3.306

Problem:    When closing a window there is a chance that deleting a scrollbar
            triggers a GUI resize, which uses the window while it is not in a
            valid state.
Solution:   Set the buffer pointer to NULL to be able to detect the invalid
            situation.  Fix a few places that used the buffer pointer
            incorrectly.

src/ex_cmds.c

@@ -3619,10 +3619,6 @@ do_ecmd(fnum, ffname, sfname, eap, newlnum, flags, oldwin)
      */
     check_arg_idx(curwin);
 
-#ifdef FEAT_SYN_HL
-    reset_synblock(curwin);	    /* remove any ownsyntax */
-#endif
-
 #ifdef FEAT_AUTOCMD
     if (!auto_buf)
 #endif