Code embedded into other sites missing syntax highlighting (BB-4806)

@cfelton reported this on the mailing list:

"""

I frequently use the "embed" option for source files to include the code in
other sites. This has been working great. Recently, most of the formatting
has been removed (no color, font, emphasis, etc)? I don't know if this is
an result of some change at bitbucket or if it is an issue with the host/site
I am using. Here is an example of a page with the embedded code from
a bitbucket repository, http://bit.ly/JPS4Zs.

Not too long ago the code looked great with syntax highlighting etc. Now
it only has the code with now highlighting.

Regards,

Chris

"""