Add syntax files from upstream vim repository

compiler/csslint.vim

@@ -0,0 +1,20 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'vim') == -1
+  
+" Vim compiler file
+" Compiler:	csslint for CSS
+" Maintainer: Daniel Moch <daniel@danielmoch.com>
+" Last Change: 2016 May 21
+
+if exists("current_compiler")
+  finish
+endif
+let current_compiler = "csslint"
+
+if exists(":CompilerSet") != 2		" older Vim always used :setlocal
+  command -nargs=* CompilerSet setlocal <args>
+endif
+
+CompilerSet makeprg=csslint\ --format=compact
+CompilerSet errorformat=%-G,%-G%f:\ lint\ free!,%f:\ line\ %l\\,\ col\ %c\\,\ %trror\ -\ %m,%f:\ line\ %l\\,\ col\ %c\\,\ %tarning\ -\ %m,%f:\ line\ %l\\,\ col\ %c\\,\ %m
+
+endif