servo: Merge #19237 - Use InvalidRule for nested rule list (from upsuper:error-nested-rule); r=emilio

This fixes [bug 1417548](https://bugzilla.mozilla.org/show_bug.cgi?id=1417548).

Apparently it makes no sense to have different error between top level rules and nested rules.

Source-Repo: https://github.com/servo/servo
Source-Revision: bf29f64bf699154c8cbb22a13495c43a49ed5f96

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 4c53e18163852c8eaaa9ad88f21e6d7d46222900

servo/components/style/stylesheets/rule_parser.rs

@@ -331,7 +331,7 @@ impl<'a, 'b, R: ParseErrorReporter> NestedRuleParser<'a, 'b, R> {
                 Ok(rule) => rules.push(rule),
                 Err((error, slice)) => {
                     let location = error.location;
-                    let error = ContextualParseError::UnsupportedRule(slice, error);
+                    let error = ContextualParseError::InvalidRule(slice, error);
                     self.context.log_css_error(self.error_context, location, error);
                 }
             }

servo/tests/unit/style/stylesheets.rs

@@ -354,9 +354,8 @@ fn test_report_error_stylesheet() {
         // When @font-feature-values is supported, this should be replaced with two errors
         (15, 25, "Invalid rule: '@font-feature-values "),
 
-        // FIXME: the message of these two should be consistent
         (16, 13, "Invalid rule: '@invalid'"),
-        (17, 29, "Unsupported rule: '@invalid'"),
+        (17, 29, "Invalid rule: '@invalid'"),
 
         (18, 34, "Invalid rule: '@supports "),
         (19, 26, "Invalid keyframe rule: 'from invalid '"),