(Bug 34798) Synced the FeedUtils.php page with mediawiki.action.history.diff.css

->Added the background,border in diff-context,diff-addedline,diff-deleted line in $styles array in the FeedUtils.php

Change-Id: Icbfb6cfc659652c146e565b760d0815640fdad64
Merge "(Bug 34798) Synced the FeedUtils.php page with mediawiki.action.history.diff.css"