style: Revert try -> r#try change.

Since we're in an inconsistent state because mako files weren't updated, and
it's really really ugly.

components/style/stylesheets/document_rule.rs

@@ -135,7 +135,7 @@ impl DocumentMatchingFunction {
         context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
-        if let Ok(url) = input.r#try(|input| CssUrl::parse(context, input)) {
+        if let Ok(url) = input.try(|input| CssUrl::parse(context, input)) {
             return Ok(DocumentMatchingFunction::Url(url));
         }