Correct cookie handling behavior

- Cookies with empty values are not to be ignored as per RFC6265
- A space should separate two cookie-pairs as per RFC6265 section
  4.2.1

components/net/cookie_storage.rs

@@ -58,10 +58,6 @@ impl CookieStorage {
             return;
         }
 
-        if cookie.cookie.value.is_empty() {
-            return;
-        }
-
         // Step 11
         if let Some(old_cookie) = old_cookie.unwrap() {
             // Step 11.3