Fix for 'Aborting layout after 100 passess' (#13359)

'Aborting layout after 100 passes.' is caused by LayoutManager falling
into a loop on rounding fractional layout slot sizes up and down while
trying to fit layout's content in the space available. LayoutManager
round always up, that causes this issue with IE9+ and Chrome. This
change helps LayoutManager to round fractional sizes down for browsers
that causes problems if rounded up.

Browsers may fall into the loop especially with a zoom level other than
100%. Not with any zoom level though. Problematic zoom level varies by
browser. OrderedLayoutExpandTest uses zoom levels other than 100%. Test
for Chrome is the only one that really is able to reproduce error
without the fix. IE9/10 would too, but the zoom level could not be set
exactly to the required 95% for IE. Test works best as a regression test
for other browsers.

Change-Id: Ie840b074df5fed5ea3b15fba9a6fd372a5c0b76a