About: Add a fallback `-webkit-calc()` to `about.css`

We forgot to run `grunt precommit` before [35834] was committed.

This change doesn't need to be backported to the 4.4 branch, as it only affects Chrome < 26, it's really just to clean up the behaviour of `grunt precommit`.

See #34663.




git-svn-id: https://develop.svn.wordpress.org/trunk@35862 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/about.css

@@ -145,6 +145,7 @@
 	display: inline-block;
 	float: none;
 	margin-right: 4.799999999%;
+	width: -webkit-calc( 47.6% - 4px );
 	width: calc( 47.6% - 4px );
 	vertical-align: middle;
 }