Build Tools: Update autoprefixer to 0.6.1.

Release Post: https://github.com/postcss/autoprefixer/releases/tag/6.1.0

Includes changes to CSS files after `grunt precommit` because of the new transition support and a new parser for gradients (see [34637]).

See #34177.
Built from https://develop.svn.wordpress.org/trunk@35563


git-svn-id: http://core.svn.wordpress.org/trunk@35527 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-beta3-35562';
+$wp_version = '4.4-beta3-35563';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.