rustdoc + rust.css preserves line breaks in inline code

[kmcallister]

$ cat foo.md
% title

The first change is to disallow importing macros from an `extern
crate` that is not at the crate root.

$ rustdoc --html-in-header=<(echo '<link rel="stylesheet" href="http://doc.rust-lang.org/rust.css">') -o . foo.md

produces

<p>The first change is to disallow importing macros from an <code>extern
crate</code> that is not at the crate root.</p>

and, since code is white-space: pre-wrap in rust.css, the line break appears in the rendered document. Probably code shouldn't set white-space independently of pre, but I'm not quite sure what the best fix is.

[lambda-fairy]

I think we can get away with just removing that line. GitHub collapses whitespace in inline code and no-one complains.