Add cssom-view.vim

This support based on latest working draft, not dev edition. The dev
edition has removed `instant` value, but it is not a big problem.

See also: http://www.w3.org/TR/2013/WD-cssom-view-20131217/

This resolves #33.

test/test.css

@@ -161,6 +161,11 @@
   display: ethiopic-numeric;
 }
 
+.cssom-view {
+  scroll-behavior: instant;
+  display: smooth;
+}
+
 .display {
   box-suppress: flow;
   display: flow-root;

test/test.html

@@ -184,6 +184,12 @@
 }
 </style>
 <style>
+.cssom-view {
+  scroll-behavior: instant;
+  display: smooth;
+}
+</style>
+<style>
 .display {
   box-suppress: flow;
   display: flow-root;