On certain installs of Windows 7, Internet Explorer 11 seems to be set
in "compatibility view" where it interprets HTML in a big-compatible
IE mode. This can be disabled by providing a explicit doctype.
This patch adds support for a theme tospecify that it needs an HTML5 doctype
and adds that to the Solstice theme. Although I haven't been able to reproduce
this bug on Windows 7, one of the bug reporters has confirmed the fix.