IE testfix: custom 404 page not displaying

On IE custom 404 pages are required to be a certain length otherwise IE just
displays the default 404 page. To reach the required 512 bytes, we can just add
empty comments after the actual text we want to display.

@bug W-1849546@
@rev rjayaramappa@
@rev goliver@
Merging origin/tbliss/master-pending-ie-testfix-404 into master