Add css-ui-4.vim

See also: http://www.w3.org/TR/2015/WD-css-ui-4-20150922/

test/test.css

@@ -588,6 +588,12 @@
   display: grabbing;
 }
 
+.ui-4 {
+  caret: fade;
+  caret-shape: fade(1em);
+  caret-animation: underscore;
+}
+
 .values {
   display: 1ch;
   display: 1vw;

test/test.html

@@ -642,6 +642,13 @@
 }
 </style>
 <style>
+.ui-4 {
+  caret: fade;
+  caret-shape: fade(1em);
+  caret-animation: underscore;
+}
+</style>
+<style>
 .values {
   display: 1ch;
   display: 1vw;