Remove duplicates to Vim 8.1 default runtime

This commit also changes file names and test code for maintainability.

Author: hail2u

README.md

@@ -0,0 +1,5 @@
+syn match cssFontProp contained "\<place-\(self\|content\|items\)\>"
+syn match cssFontProp contained "\<\(row-\)\=gap\>"
+syn keyword cssFontAttr contained safe unsafe legacy
+syn match cssFontAttr contained "\<self-\(start\|end\)\>"
+syn match cssFontAttr contained "\<space-evenly\>"

after/syntax/css/align-3.vim

@@ -2,4 +2,3 @@ syn match cssBoxProp contained "\<overflow-\(style\|x\|y\)\>"
 syn match cssBoxProp contained "\<rotation\(-point\)\=\>"
 syn keyword cssBoxAttr contained scrollbar panner marquee
 syn match cssBoxAttr contained "\<ruby\(-\(base\(-group\)\=\|text\(-group\)\=\)\)\=\>"
-syn match cssBoxAttr contained "\<no-\(display\|content\)\>"