Prevent inclusion of whitespace character after macro_rules ident

Author: GuillaumeGomez

src/librustdoc/html/highlight.rs

@@ -136,6 +136,7 @@ fn can_merge(class1: Option<Class>, class2: Option<Class>, text: &str) -> bool {
     match (class1, class2) {
         (Some(c1), Some(c2)) => c1.is_equal_to(c2),
         (Some(Class::Ident(_)), None) | (None, Some(Class::Ident(_))) => true,
+        (Some(Class::Macro(_)), _) => false,
         (Some(_), None) | (None, Some(_)) => text.trim().is_empty(),
         (None, None) => true,
     }