style: Parse the legacy border attribute per the legacy HTML specification.

Additionally, this patch cleans up some miscellaneous formatting issues
and refactors files in `layout/css/` somewhat to eliminate needless
levels of indirection. It also fixes our handling of presentational
hints that only apply if border is nonzero.

components/util/str.rs

@@ -61,7 +61,8 @@ pub static HTML_SPACE_CHARACTERS: StaticCharVec = &[
     '\u000d',
 ];
 
-pub fn split_html_space_chars<'a>(s: &'a str) -> Filter<'a, &'a str, CharSplits<'a, StaticCharVec>> {
+pub fn split_html_space_chars<'a>(s: &'a str)
+                                  -> Filter<'a, &'a str, CharSplits<'a, StaticCharVec>> {
     s.split(HTML_SPACE_CHARACTERS).filter(|&split| !split.is_empty())
 }
 
@@ -76,7 +77,6 @@ fn do_parse_integer<T: Iterator<char>>(input: T) -> Option<i64> {
         }
     }
 
-
     let mut input = input.skip_while(|c| {
         HTML_SPACE_CHARACTERS.iter().any(|s| s == c)
     }).peekable();