Fix IE9 issue with box-sizing: initial
Fix IE9 issue with box-sizing: initial

IE9 (and maybe other versions of IE) apparently do not support
`box-sizing: initial`, and the initial (default) value must be
named explicitly as `box-sizing: content-box`.

denodster/viewer.js,lakenen/viewer.js,vdclouis/viewer.js,lakenen/viewer.js,denodster/viewer.js,box/viewer.js,vdclouis/viewer.js,vdclouis/viewer.js,denodster/viewer.js,box/viewer.js,box/viewer.js,lakenen/viewer.js