servo: Merge #18759 - stylo: Keep unshipping stuff (from emilio:keep-unshipping-dont-stop); r=upsuper

From bug 1396066

Source-Repo: https://github.com/servo/servo
Source-Revision: 90d0afc61485b352b557efeabb52505bd1bd6417

servo/components/style/parser.rs

@@ -130,6 +130,11 @@ impl<'a> ParserContext<'a> {
         };
         context.error_reporter.report_error(self.url_data, location, error)
     }
+
+    /// Returns whether this is a chrome stylesheets.
+    pub fn in_chrome_stylesheet(&self) -> bool {
+        self.url_data.is_chrome()
+    }
 }
 
 // XXXManishearth Replace all specified value parse impls with impls of this