Update runtime files.
diff --git a/runtime/syntax/prolog.vim b/runtime/syntax/prolog.vim
index 58b279b..93aba4d 100644
--- a/runtime/syntax/prolog.vim
+++ b/runtime/syntax/prolog.vim
@@ -1,7 +1,7 @@
" Vim syntax file
" Language: PROLOG
" Maintainer: Anton Kochkov <anton.kochkov@gmail.com>
-" Last Change: 2019 Aug 29
+" Last Change: 2021 Jan 05
" There are two sets of highlighting in here:
" If the "prolog_highlighting_clean" variable exists, it is rather sparse.
@@ -21,16 +21,16 @@
" Very simple highlighting for comments, clause heads and
" character codes. It respects prolog strings and atoms.
-syn region prologCComment start=+/\*+ end=+\*/+
-syn match prologComment +%.*+
+syn region prologCComment start=+/\*+ end=+\*/+ contains=@Spell
+syn match prologComment +%.*+ contains=@Spell
if !exists("prolog_highlighting_no_keyword")
syn keyword prologKeyword module meta_predicate multifile dynamic
endif
syn match prologCharCode +0'\\\=.+
-syn region prologString start=+"+ skip=+\\\\\|\\"+ end=+"+
+syn region prologString start=+"+ skip=+\\\\\|\\"+ end=+"+ contains=@Spell
syn region prologAtom start=+'+ skip=+\\\\\|\\'+ end=+'+
-syn region prologClause matchgroup=prologClauseHead start=+^\s*[a-z]\w*+ matchgroup=Normal end=+\.\s\|\.$+ contains=ALLBUT,prologClause
+syn region prologClause matchgroup=prologClauseHead start=+^\s*[a-z]\w*+ matchgroup=Normal end=+\.\s\|\.$+ contains=ALLBUT,prologClause contains=@NoSpell
if !exists("prolog_highlighting_clean")