Sass::Script::Color#to_s returns the human readable form when it belongs to the set of HTML4 colors.
This means that the following:
This breaks the btn and breadcrumb classes on IE (among others).
Fix ie_hex_str to work with HTML4 colors
Add tests for ie_hex_str
I took the liberty of adding some tests, related to the current bug fix. I used the default ruby test framework and I can confirm they pass both on ruby 1.9.2 and 1.8.7.