Prevent users from zooming in IE Mobile

Fixes #7499

According to https://msdn.microsoft.com/en-us/library/dn629259(v=vs.85).aspx,
“the minimum-scale, maximum-scale, and initial-scale properties are currently
unsupported for Internet Explorer for Windows Phone“.

For further information on the viewport properties see
https://drafts.csswg.org/css-device-adapt/#viewport-meta

closes #7589